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Shareholders' Equity / Partners' Capital
12 Months Ended
Dec. 31, 2018
Equity [Abstract]  
Shareholders' Equity / Partners' Capital
Shareholders’ Equity / Partners' Capital

When the Company issues common or preferred shares, the Operating Partnership issues an equivalent number of units of partnership interest of a corresponding class to AH4R, with the Operating Partnership receiving the net proceeds from the share issuances.

Class A Common Shares / Units

Class A units represent voting equity interests in the Operating Partnership. Holders of Class A units in the Operating Partnership have the right to redeem the units for cash or, at the election of the Company, exchange the units for AH4R's Class A common shares on a one-for-one basis. AH4R owned 84.3% and 83.8% of the total 351,966,447 and 342,099,865 Class A units outstanding as of December 31, 2018 and 2017, respectively.

During the third quarter of 2017, the Company issued 13,800,000 Class A common shares of beneficial interest, $0.01 par value per share, in an underwritten public offering, raising gross proceeds of $312.0 million before offering costs of approximately $9.2 million. The Operating Partnership issued an equivalent number of corresponding Class A units to AH4R in exchange for the net proceeds from the issuance.

During the first quarter of 2017, the Company issued 14,842,982 Class A common shares of beneficial interest, $0.01 par value per share, in an underwritten public offering and concurrent private placement, raising gross proceeds to the Company of $336.5 million after underwriter's discount and before offering costs of approximately $0.4 million. The Operating Partnership issued an equivalent number of corresponding Class A units to AH4R in exchange for the net proceeds from the issuance.

During the first quarter of 2016, the Company issued 36,546,170 Class A common shares, $0.01 par value per share, in connection with the ARPI Merger. The Operating Partnership issued an equivalent number of corresponding Class A units to AH4R in exchange for the transaction consideration. During the first quarter of 2016, the Operating Partnership also issued 1,343,843 Class A units to certain former ARPI employees in connection with the ARPI Merger (see Note 11).

At-the-Market Common Share Offering Program
During the fourth quarter of 2016, the Company established an at-the-market common share offering program under which we were able to issue Class A common shares from time to time through various sales agents up to an aggregate of $400.0 million (the "Original At-the-Market Program"). The program was established in order to use the net proceeds from share issuances to repay borrowings against the Company’s revolving credit and term loan facilities, to acquire and renovate single-family properties and for related activities in accordance with the Company’s business strategy, and for working capital and general corporate purposes. The program may be suspended or terminated by the Company at any time. During the year ended December 31, 2017, the Company issued and sold 2.0 million Class A common shares under the Original At-the-Market Program for gross proceeds of $46.2 million, or $22.74 per share, and net proceeds of $45.6 million, after commissions and other expenses of approximately $0.6 million. During the year ended December 31, 2016, the Company issued and sold 4.9 million Class A common shares for gross proceeds of $104.0 million, or $21.13 per share, and net proceeds of $102.8 million, after commissions and other expenses of approximately $1.2 million. The Operating Partnership issued an equivalent number of corresponding Class A units to AH4R in exchange for the net proceeds from the share issuances. The Original At-the-Market Program was replaced during the third quarter of 2017 with an at-the-market common share offering program with a $500.0 million capacity with the same terms (the "At-the-Market Program"). As of December 31, 2018, no shares have been issued under the At-the-Market Program and $500.0 million remained available for future share issuances.

Share Repurchase Program

During the third quarter of 2015, the Company announced that its board of trustees approved a share repurchase program (the "Original Share Repurchase Program") authorizing us to repurchase up to $300.0 million of our outstanding Class A common shares from time to time in the open market or in privately negotiated transactions. The program does not have an expiration date, but may be suspended or discontinued at any time without notice. All repurchased shares are constructively retired and returned to an authorized and unissued status. The Operating Partnership funds the repurchases and constructively retires an equivalent number of corresponding Class A units. This program was replaced during the first quarter of 2018 when the Company's board of trustees approved a new share repurchase program (the "Share Repurchase Program") with the same terms, authorizing the repurchase of up to $300.0 million of our outstanding Class A common shares and up to $250.0 million of our outstanding preferred shares. During the year ended December 31, 2018, the Company repurchased and retired 1.8 million of our Class A common shares on a settlement basis, in accordance with the Share Repurchase Program at a weighted-average price of $19.36 per share and a total price of $34.9 million. During the year ended December 31, 2017, we did not repurchase or retire any of our Class A common shares. During the year ended December 31, 2016, we repurchased and retired 6.2 million of our Class A common shares, on a settlement date basis, in accordance with the Original Share Repurchase Program at a weighted-average price of $15.44 per share and a total price of $96.0 million. As of December 31, 2018, we had a remaining repurchase authorization of up to $265.1 million of our outstanding Class A common shares and up to $250.0 million of our outstanding preferred shares under the Share Repurchase Program.

Class B Common Shares

Former AH LLC members received 635,075 Class B common shares in connection with their contributions of properties and funds to the Company. The Operating Partnership issued an equivalent number of corresponding Class A units to AH4R in exchange for the proceeds and properties contributed in the transaction. Each Class B common share generally entitles the holder to 50 votes on all matters that the holders of Class A common shares are entitled to vote. The issuance of Class B common shares to former AH LLC members allows former AH LLC members a voting right associated with their investment in the Company no greater than if they had solely received Class A common shares. Additionally, when the voting interest from Class A common shares and Class B common shares are added together, a shareholder is limited to a 30% total voting interest. Each Class B common share has the same economic interest as a Class A common share.

Preferred Shares

As of December 31, 2018 and 2017, the Company had the following series of preferred shares outstanding (in thousands, except share data):
 
 
 
 
 
 
 
 
December 31, 2018
 
December 31, 2017
Series
 
Issuance Date
 
Earliest Redemption Date
 
Dividend Rate
 
Outstanding Shares
 
Liquidation Value
 
Outstanding Shares
 
Liquidation Value (1)
Series C participating preferred shares (2)
 
N/A
 
N/A
 
N/A

 

 
$

 
7,600,000

 
$
218,236

Series D perpetual preferred shares
 
5/24/2016
 
5/24/2021
 
6.500
%
 
10,750,000

 
268,750

 
10,750,000

 
268,750

Series E perpetual preferred shares
 
6/29/2016
 
6/29/2021
 
6.350
%
 
9,200,000

 
230,000

 
9,200,000

 
230,000

Series F perpetual preferred shares
 
4/24/2017
 
4/24/2022
 
5.875
%
 
6,200,000

 
155,000

 
6,200,000

 
155,000

Series G perpetual preferred shares
 
7/17/2017
 
7/17/2022
 
5.875
%
 
4,600,000

 
115,000

 
4,600,000

 
115,000

Series H perpetual preferred shares
 
9/19/2018
 
9/19/2023
 
6.250
%
 
4,600,000

 
115,000

 

 

Total preferred shares
 
 
 
 
 
 
 
35,350,000

 
$
883,750

 
38,350,000

 
$
986,986

(1)
Liquidation value reflects initial liquidation value of $25.00 per share, which in the case of the Series C participating preferred shares was adjusted by an amount equal to 50% of the cumulative change in value of an index based on the purchase prices of single-family properties located in our top 20 markets.
(2)
All of the outstanding Series C participating preferred shares were converted into 10,848,827 Class A common shares on April 5, 2018, based on a conversion ratio of 1.4275 common shares per preferred share in accordance with the conversion terms in the Articles Supplementary.

Perpetual Preferred Shares / Units

Perpetual preferred shares represent non-voting preferred equity interests in the Company and entitle holders to a cumulative annual cash dividend equal to 6.5% for the Series D cumulative redeemable perpetual preferred shares ("Series D perpetual preferred shares"), 6.35% for the Series E cumulative redeemable perpetual preferred shares ("Series E perpetual preferred shares"), 5.875% for the Series F cumulative redeemable perpetual preferred shares ("Series F perpetual preferred shares"), 5.875% for the Series G cumulative redeemable perpetual preferred shares ("Series G perpetual preferred shares") and 6.25% for the Series H cumulative redeemable perpetual preferred shares ("Series H perpetual preferred shares"), which is applied to the liquidation preference at issuance of $25 per share. The Operating Partnership issues an equivalent number of corresponding perpetual preferred units for the given class to AH4R in exchange for the net proceeds from the share issuances. The Company may, at its option, redeem the perpetual preferred shares for cash, in whole or in part, from time to time, at any time on or after May 24, 2021, for the Series D perpetual preferred shares, June 29, 2021, for the Series E perpetual preferred shares, April 24, 2022, for the Series F perpetual preferred shares, July 17, 2022, for the Series G perpetual preferred shares and September 19, 2023, for the Series H perpetual preferred shares or within 120 days after the occurrence of a change in control at a redemption price equal to the $25 per share liquidation preference, plus any accumulated and unpaid dividends.

During the third quarter of 2018, the Company issued 4,600,000 6.25% Series H cumulative redeemable perpetual preferred shares in an underwritten public offering, raising gross proceeds of $115.0 million before offering costs of approximately $4.4 million, with a liquidation preference of $25.00 per share. The Operating Partnership issued an equivalent number of the same class of perpetual preferred units to AH4R in exchange for the net proceeds from the share issuance.

During the third quarter of 2017, the Company issued 4,600,000 5.875% Series G cumulative redeemable perpetual preferred shares in an underwritten public offering, raising gross proceeds of $115.0 million before offering costs of approximately $4.1 million, with a liquidation preference of $25.00 per share. The Operating Partnership issued an equivalent number of the same class of perpetual preferred units to AH4R in exchange for the net proceeds from the share issuance.

During the second quarter of 2017, the Company issued 6,200,000 5.875% Series F cumulative redeemable perpetual preferred shares in an underwritten public offering, raising gross proceeds of $155.0 million before offering costs of approximately $5.3 million, with a liquidation preference of $25.00 per share. The Operating Partnership issued an equivalent number of the same class of perpetual preferred units to AH4R in exchange for the net proceeds from the share issuance.

During the second quarter of 2016, the Company issued 9,200,000 6.35% Series E perpetual preferred shares in an underwritten public offering, raising gross proceeds of $230.0 million before offering costs of $7.5 million. The Operating Partnership issued an equivalent number of the same class of perpetual preferred units to AH4R in exchange for the net proceeds from the share issuance.

Also during the second quarter of 2016, the Company issued 10,750,000 6.5% Series D perpetual preferred shares in an underwritten public offering and concurrent private placement, raising gross proceeds of $268.8 million before offering costs of $8.5 million. The Operating Partnership issued an equivalent number of the same class of perpetual preferred units to AH4R in exchange for the net proceeds from the share issuance.

Participating Preferred Shares / Units

Participating preferred shares represented non-voting preferred equity interests in the Company and entitled holders to a cumulative annual cash dividend equal to 5.0% for the Series A and B participating preferred shares and 5.5% for the Series C participating preferred shares of an initial liquidation preference of $25 per share. The Operating Partnership issued an equivalent number of corresponding participating preferred units to AH4R in exchange for the net proceeds from the share issuance. Any time between March 31, 2018, and March 31, 2021 (the "initial redemption period"), the Company had the option to redeem the Series C participating preferred shares for cash or Class A common shares, at a redemption price equal to the initial liquidation preference, adjusted by an amount equal to 50% of the cumulative change in value of an index based on the purchase prices of single-family properties located in our top 20 markets (the "HPA adjustment"). During the initial redemption period, the amount payable upon redemption was subject to a cap, such that the total internal rate of return, when considering the initial liquidation preference, the HPA adjustment and dividends up to, but excluding, the date of redemption, did not exceed 9.0%. Because the HPA adjustment meets the definition of a derivative under ASC 815, Derivatives and Hedging, and is not clearly and closely related to the economic characteristics and risks of the underlying preferred shares, the fair value of the HPA adjustment has been reflected as a liability in the consolidated balance sheets and is adjusted to fair value each period and included in remeasurement of participating preferred shares in the consolidated statements of operations (see Note 15).

During the second quarter of 2014, the Company issued 7,600,000 5.5% Series C participating preferred shares in an underwritten public offering and concurrent private placement, raising gross proceeds of $190.0 million before offering costs of $9.7 million. The Operating Partnership issued an equivalent number of the same class of participating preferred units to AH4R in exchange for the net proceeds from the share issuance.

During the fourth quarter of 2013 and the first quarter of 2014, the Company issued 4,400,000 5.0% Series B participating preferred shares in an underwritten public offering which raised gross proceeds of $110.0 million before offering costs of $6.6 million. The Operating Partnership issued an equivalent number of the same class of participating preferred units to AH4R in exchange for the net proceeds from the share issuance.

During the fourth quarter of 2013, the Company issued 5,060,000 5.0% Series A participating preferred shares in an underwritten public offering, which raised gross proceeds of $126.5 million before offering costs of $7.3 million. The Operating Partnership issued an equivalent number of the same class of participating preferred units to AH4R in exchange for the net proceeds from the share issuance.

Redemptions of Participating Preferred Shares / Units

On April 5, 2018, the Company redeemed all 7,600,000 shares of the outstanding 5.5% Series C participating preferred shares through a conversion of those participating preferred shares into Class A common shares of beneficial interest, $0.01 par value, in accordance with the conversion terms in the Articles Supplementary. This resulted in 10,848,827 Class A common shares issued from the conversion, based on a conversion ratio of 1.4275 Class A common shares issued per Series C participating preferred share. The Operating Partnership also redeemed its corresponding Series C participating preferred units through a conversion into Class A units on April 5, 2018. The conversion ratio was calculated by dividing (1) the initial liquidation preference on the Series C participating preferred shares, as adjusted by an amount equal to 50% of the cumulative change in value of an index based on the purchase prices of single-family properties located in our top 20 markets (adjusted for a maximum 9.0% internal rate of return), plus unaccrued dividends by (2) the one-day volume weighted-average price (“VWAP”) of the Company’s Class A common shares on March 29, 2018, the date the Company delivered the required notice of redemption. As a result of the redemption, the Company recorded a $32.2 million allocation of income to the Series C participating preferred shareholders in the second quarter of 2018, which represents the initial liquidation value of the Series C participating preferred shares in excess of the original equity carrying value of the Series C participating preferred shares as of the redemption date. The original equity carrying value of the Series C participating preferred shares was net of the initial bifurcated home price appreciation derivative liability and offering costs.

On October 3, 2017, the Company redeemed all 5,060,000 shares of the outstanding 5.0% Series A participating preferred shares and all 4,400,000 shares of the outstanding 5.0% Series B participating preferred shares through a conversion of those participating preferred shares into Class A common shares of beneficial interest, $0.01 par value, in accordance with the conversion terms in the Articles Supplementary. This resulted in 12,398,276 total Class A common shares issued from the conversion, based on a conversion ratio of 1.3106 Class A common shares issued per Series A and B participating preferred share. The Operating Partnership also redeemed its corresponding Series A and B participating preferred units through a conversion into Class A units on October 3, 2017. The conversion ratio was calculated by dividing (1) the initial liquidation preference on the Series A and B participating preferred shares, as adjusted by an amount equal to 50% of the cumulative change in value of an index based on the purchase prices of single-family properties located in our top 20 markets, plus unaccrued dividends by (2) the one-day volume weighted-average price (“VWAP”) of the Company’s Class A common shares on September 27, 2017, the date the Company delivered the required notice of conversion. As a result of the redemption, the Company recorded a $42.4 million allocation of income to the Series A and B participating preferred shareholders during the year ended December 31, 2017, which represents the initial liquidation value of the Series A and B participating preferred shares in excess of the original equity carrying value of the Series A and B participating preferred shares as of the redemption date. The original equity carrying value of the Series A and B participating preferred shares was net of the initial bifurcated home price appreciation derivative liability and offering costs.

Conversion of Series C Convertible Units into Class A Units

The Series C convertible units represented voting equity interests in the Operating Partnership owned by former AH LLC members. On February 28, 2016, the third anniversary of their original issue date, the 31,085,974 Series C convertible units converted into Class A units on a one-for-one basis in accordance with their terms.

Conversion of Series E Convertible Units into Series D Convertible Units

The Series E convertible units represented non-voting equity interests in the Operating Partnership. The Series E convertible units did not participate in any distributions and were convertible into Series D convertible units, subject to an earn-out provision, which was met in full and, therefore, the 4,375,000 Series E convertible units were converted into Series D convertible units on a one-for-one basis on February 29, 2016. The fair value of the Series D convertible units was estimated using a Monte Carlo simulation model, which was primarily driven by the most recent trading price of the Company’s Class A common shares into which the Series D convertible units are ultimately convertible. Based on this valuation, the conversion of Series E convertible units into Series D convertible units resulted in a gain of $11.5 million which was recorded in gain on conversion of Series E units within the consolidated statements of operations. Additionally, the Series E convertible units had a $2.8 million contingent beneficial conversion feature that represents a return to the Series E convertible unit holders in the form of additional noncontrolling interest, calculated as the difference between the estimated fair value of the Series D units and the Class A units at the time of the conversion of the Series E units into Series D units in February 2016. The contingent beneficial conversion feature was recognized when the contingency was met, which occurred when the Series D units converted into Class A units on September 30, 2016.

Conversion of Series D Convertible Units into Class A Units

The Series D convertible units represented non-voting equity interests in the Operating Partnership owned by former AH LLC members and began participating in distributions, representing 70% of distributions declared on Class A units, 30 months after their issuance. The Series D convertible units were automatically convertible into Class A units on a one-for-one basis only after the later of (1) 30 months after the date of issuance and (2) the earlier of (i) the date on which adjusted funds from operations per Class A common share aggregated to $0.80 or more over four consecutive quarters following the original issuance date of the units and (ii) the date on which the daily closing price of our Class A common shares on the NYSE averaged $18.00 or more for two consecutive quarters following the original issuance date of the units. On September 30, 2016, the above-referenced conversion contingency was met and the 8,750,000 Series D convertible units (including the 4,375,000 Series E units that converted into Series D units on February 29, 2016) were converted into Class A units on a one-for-one basis, which resulted in a $7.6 million noncash charge (including $2.8 million from the Series E units that converted to Series D units on February 29, 2016) that was included in noncontrolling interest within the consolidated statements of operations. The noncash charge relates to a contingent beneficial conversion feature that represents a return to the Series D convertible unit holders in the form of additional noncontrolling interest, calculated as the difference between the estimated fair value of the Series D units and the Class A units at the time of their respective issuances, which was recognized when the contingency was met.

Distributions

To qualify as a REIT, AH4R is required to distribute annually to our shareholders at least 90% of our REIT taxable income, determined without regard to the deduction for dividends paid and excluding net capital gains, and to pay tax at regular corporate rates to the extent that we annually distribute less than 100% of our REIT taxable income. AH4R intends to pay quarterly dividends to our shareholders; and the Operating Partnership intends to pay quarterly distributions to its unitholders, including AH4R, which distributions are, in the aggregate, approximately equal or exceed AH4R's REIT taxable income in the relevant year.

As a REIT we are required to distribute annually at least 90% of our REIT taxable income. We currently intend to distribute approximately 100% of our REIT taxable income. We expect to use our NOL to reduce our REIT taxable income in future years. As of December 31, 2018, AH4R had a NOL for U.S. federal income tax purposes of approximately $275.0 million. Once our NOL is fully used, we may be required to increase AH4R’s distributions to comply with REIT distribution requirements and our current policy of distributing approximately all of our REIT taxable income.

During the year ended December 31, 2018, the Company's board of trustees declared distributions that totaled $0.20 per share on our Class A and Class B common shares, $0.34 per share on our 5.5% Series C participating preferred shares (prior to their conversion to Class A common shares on April 5, 2018), $1.63 per share on our 6.5% Series D perpetual preferred shares, $1.59 per share on our 6.35% Series E perpetual preferred shares, $1.47 per share on our 5.875% Series F perpetual preferred shares, $1.47 per share on our 5.875% Series G perpetual preferred shares and $0.44 per share on our 6.25% Series H perpetual preferred shares, which represents the initial distribution on our 6.25% Series H perpetual preferred shares that was declared on November 1, 2018, and relates to the initial distribution period that commenced on and includes the original issuance date of September 19, 2018, through December 31, 2018. During the year ended December 31, 2017, the Company's board of trustees declared distributions that totaled $0.20 per share on our Class A and Class B common shares, $0.94 per share on our 5.0% Series A participating preferred shares (prior to their conversion to Class A common shares on October 3, 2017), $0.94 per share on our 5.0% Series B participating preferred shares (prior to their conversion to Class A common shares on October 3, 2017), $1.38 per share on our 5.5% Series C participating preferred shares, $1.63 per share on our 6.5% Series D perpetual preferred shares, $1.59 per share on our 6.35% Series E perpetual preferred shares, $1.01 per share on our 5.875% Series F perpetual preferred shares and $0.67 per share on our 5.875% Series G perpetual preferred shares. During the year ended December 31, 2016, the Company's board of trustees declared distributions that totaled $0.20 per share on our Class A and Class B common shares, $1.25 per share on our 5.0% Series A participating preferred shares, $1.25 per share on our 5.0% Series B participating preferred shares, $1.38 per share on our 5.5% Series C participating preferred shares, $0.98 per share on our 6.5% Series D perpetual preferred shares, $0.80 per share on our 6.35% Series E perpetual preferred shares, $0.07 per unit on our Series C convertible units (prior to their conversion to Class A units on February 28, 2016) and $0.11 per unit on our Series D convertible units (prior to their conversion to Class A units on September 30, 2016). The Operating Partnership funds the payment of distributions, and an equivalent amount of distributions were declared on the corresponding Operating Partnership units.

Noncontrolling Interest

Noncontrolling interest as reflected in the Company’s consolidated balance sheets primarily consists of the interests held by former AH LLC members in units in the Operating Partnership. Former AH LLC members owned 54,243,317 and 54,276,644, or approximately 15.4% and 15.9%, of the total 351,966,447 and 342,099,865 Class A units in the Operating Partnership as of December 31, 2018 and 2017, respectively. Noncontrolling interest also includes interests held by non-affiliates in Class A units in the Operating Partnership. Non-affiliate Class A unitholders owned 1,073,509, or approximately 0.3% of the total 351,966,447 and 342,099,865 Class A units in the Operating Partnership as of December 31, 2018 and 2017, respectively. Also included in noncontrolling interest as of December 31, 2017, was the outside ownership interest in a consolidated subsidiary of the Operating Partnership, which was liquidated during the second quarter of 2018.

The following table summarizes the income or loss allocated to noncontrolling interests as reflected in the Company's consolidated statements of operations for the years ended December 31, 2018, 2017 and 2016 (in thousands):
 
For the Years Ended December 31,
 
2018
 
2017
 
2016
 Preferred income allocated to Series C convertible units
$

 
$

 
$
3,027

 Net income (loss) allocated to Class A units
4,424

 
(4,648
)
 
(6,417
)
 Net income allocated to Series D convertible units

 

 
134

 Beneficial conversion feature related to Series D and E convertible units

 

 
7,569

 Net (loss) income allocated to noncontrolling interest in a consolidated subsidiary
(259
)
 
141

 
(562
)
 
$
4,165

 
$
(4,507
)
 
$
3,751



Noncontrolling interest as reflected in the Operating Partnership's consolidated balance sheets consisted solely of the outside ownership interest in a consolidated subsidiary of the Operating Partnership, which was liquidated during the second quarter of 2018. Income and loss allocated to the Operating Partnership's noncontrolling interest is reflected in noncontrolling interest within the Operating Partnership's consolidated statements of operations. The Operating Partnership units owned by former AH LLC members and non-affiliates that are reflected as noncontrolling interest in the Company's consolidated balance sheets are reflected as limited partner capital in the Operating Partnership's consolidated balance sheets.

2012 Equity Incentive Plan

In 2012, the Company adopted the 2012 Equity Incentive Plan (the "Plan") to provide persons with an incentive to contribute to the success of the Company and to operate and manage our business in a manner that will provide for the Company's long-term growth and profitability. The Plan provides for the issuance of up to 6,000,000 Class A common shares through the grant of a variety of awards including stock options, stock appreciation rights, restricted stock, unrestricted shares, dividend equivalent rights and performance-based awards. The Plan terminates in November 2022, unless it is earlier terminated by the Company's board of trustees. The Company's employees are compensated through the Operating Partnership, including share-based compensation. When the Company issues Class A common shares under the Plan, the Operating Partnership issues an equivalent number of Class A units to AH4R.

During the year ended December 31, 2018, the Company granted stock options for 140,000 Class A common shares and 304,400 restricted stock units to certain employees of the Company. During the year ended December 31, 2017, the Company granted stock options for 385,200 Class A common shares and 174,400 restricted stock units to certain employees of the Company. During the year ended December 31, 2016, the Company granted stock options for 708,000 Class A common shares and 74,100 restricted stock units to certain employees of the Company.

All of the options and restricted stock units granted during the years ended December 31, 2018, 2017 and 2016, vest over a four-year service period, and the options expire 10 years from the date of grant. Noncash share-based compensation expense related to these options is based on the estimated fair value on the date of grant and is recognized in expense over the service period.

The following table summarizes stock option activity under the Plan for the years ended December 31, 2018, 2017 and 2016:
 
Shares
 
Weighted- Average Exercise Price
 
Weighted- Average Remaining Contractual Life (in years)
 
Aggregate Intrinsic Value (1) (in thousands)
Options outstanding at December 31, 2015
2,484,400

 
$
16.22

 
8.0
 
$
1,225

Granted
708,000

 
14.15

 
 
 
 
Exercised
(196,000
)
 
16.18

 
 
 
790

Forfeited
(169,900
)
 
16.38

 
 
 
 
Options outstanding at December 31, 2016
2,826,500

 
$
15.69

 
7.6
 
$
14,956

Granted
385,200

 
23.38

 
 
 
 
Exercised
(74,000
)
 
15.65

 
 
 
520

Forfeited
(85,250
)
 
16.24

 
 
 
 
Options outstanding at December 31, 2017
3,052,450

 
$
16.65

 
6.9
 
$
16,421

Granted
140,000

 
19.40

 
 
 
 
Exercised
(769,875
)
 
16.07

 
 
 
4,754

Forfeited
(170,300
)
 
17.93

 
 
 
 
Options outstanding at December 31, 2018
2,252,275

 
$
16.92

 
6.1
 
$
7,713

Options exercisable at December 31, 2018
1,569,800

 
$
16.21

 
5.4
 
$
6,018

(1)
Intrinsic value for activities other than exercises is defined as the difference between the grant price and the market value on the last trading day of the period for those stock options where the market value is greater than the exercise price. For exercises, intrinsic value is defined as the difference between the grant price and the market value on the date of exercise.

The following table summarizes the Black-Scholes Option Pricing Model inputs used for valuation of the stock options for Class A common shares granted during the years ended December 31, 2018, 2017 and 2016:
 
2018
 
2017
 
2016
Weighted-average fair value
$
3.03

 
$
3.82

 
$
2.82

Expected term (years)
 
7.0

 
 
7.0

 
 
7.0

Dividend yield
 
3.0
%
 
 
3.0
%
 
 
3.0
%
Volatility
 
18.9
%
 
 
21.3
%
 
 
27.3
%
Risk-free interest rate
 
2.8
%
 
 
2.2
%
 
 
1.5
%


The following table summarizes the activity that relates to the Company’s restricted stock units under the Plan for the years ended December 31, 2018, 2017 and 2016:
 
2018
 
2017
 
2016
Restricted stock units at beginning of period
243,875

 
130,150

 
91,650

Units awarded
304,400

 
174,400

 
74,100

Units vested
(80,125
)
 
(42,475
)
 
(27,250
)
Units forfeited
(95,775
)
 
(18,200
)
 
(8,350
)
Restricted stock units at end of the period
372,375

 
243,875

 
130,150



For the years ended December 31, 2018, 2017 and 2016, total non-cash share-based compensation expense related to stock options and restricted stock units was $3.4 million, $4.2 million and $3.6 million, respectively, of which $2.1 million, $2.6 million and $2.1 million, respectively, related to corporate administrative employees and was included in general and administrative expense and $1.3 million, $1.6 million and $1.5 million, respectively, related to centralized and field property management employees and was included in property management expenses within the consolidated statements of operations.

As of December 31, 2018, there was a total unrecognized compensation cost of $1.4 million for unvested stock options and $5.6 million for unvested restricted stock units. The unrecognized compensation cost for unvested stock options and restricted stock units is expected to be recognized over a weighted-average period of 2.00 and 2.78 years, respectively.