Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
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Unrecognized cost of unvested share-based compensation awards.

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- Definition

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date.

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

Date the equity-based award expires, in CCYY-MM-DD format.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Number of share instruments newly issued under a share-based compensation plan.

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Incentive Compensation Plan - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions																															1 Months Ended		12 Months Ended
	Mar. 24, 2017	Feb. 23, 2017	Dec. 19, 2016	Sep. 30, 2016	Sep. 19, 2016	Jun. 07, 2016	Mar. 01, 2016	Mar. 01, 2016	Mar. 01, 2016	Feb. 18, 2016	Dec. 30, 2015	Jun. 26, 2015	Feb. 20, 2015	Feb. 20, 2015	Feb. 05, 2015	Jan. 29, 2015	Jan. 26, 2015	Jan. 15, 2015	Nov. 18, 2014	Apr. 08, 2014	Mar. 25, 2014	Mar. 05, 2014	Jan. 27, 2014	Jan. 01, 2014	Aug. 16, 2013	May 31, 2013	Mar. 01, 2013	Jan. 28, 2013	Jan. 02, 2012	Apr. 01, 2011	Feb. 24, 2012	Nov. 21, 2011	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Price (in dollars per share)																																	$ 12.99	$ 9.88	$ 8.41
Maximum number of shares that are available to be awarded																																	5,000,000
Vesting period of restricted stock		0 years								0 years	0 years						0 years						0 years					1 year			1 year
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant																																	3,365,572
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Price (in dollars per share)											$ 9.18																						$ 14.32
Allocated Share-based Compensation Expense																																	$ 3.8
Compensation expense																																		$ 3.2	$ 1.4
Unrecognized compensation cost related to unvested restricted stock																																	$ 3.0
75 Percent of Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Price (in dollars per share)		$ 13.29
25 Percent of Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Price (in dollars per share)		$ 15.09
March 24, 2017 Grant 4 [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)	5,000
Grant Price (in dollars per share)	$ 12.99
Vesting Date	Mar. 24, 2020
Number of Equal Vesting Periods	1
March 24, 2017 Grant 3 [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)	7,000
Grant Price (in dollars per share)	$ 12.99
Vesting Date	Aug. 31, 2017
Number of Equal Vesting Periods	1
March 24, 2017 Grant 2 [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)	7,000
Grant Price (in dollars per share)	$ 12.99
Vesting Date	Mar. 24, 2020
Number of Equal Vesting Periods	1
March 24, 2017 Grant 1 [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)	7,000
Grant Price (in dollars per share)	$ 12.99
Vesting Date	Aug. 31, 2017
Number of Equal Vesting Periods	1
Executive [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)			15,000	10,000	33,000	10,000	10,000	5,000	20,000	18,348		1,000	34,200	10,000				20,000	3,500	27,500	46,000	5,000		12,626	3,000	45,000	10,000		100,000	25,000		10,000
Grant Price (in dollars per share)			$ 13.96	$ 10.09	$ 10.02	$ 9.34	$ 8.84	$ 8.84	$ 8.84	$ 8.43		$ 9.84	$ 8.45	$ 8.45				$ 8.38	$ 9.26	$ 8.89	$ 9.18	$ 8.75		$ 8.82	$ 7.57	$ 7.21	$ 7.35		$ 5.26	$ 6.82		$ 4.41
Vesting Date			Dec. 19, 2019	Sep. 30, 2019	Sep. 19, 2019	Jun. 07, 2019	Mar. 01, 2019	Mar. 01, 2019	Aug. 31, 2017	Dec. 31, 2016		Jun. 26, 2018	Dec. 31, 2015	Aug. 31, 2017				Jan. 15, 2017	Nov. 17, 2017	Apr. 08, 2017	Mar. 24, 2017	Mar. 04, 2017		Dec. 31, 2014	Aug. 16, 2016	May 31, 2016	Mar. 01, 2016		Jan. 01, 2016	Apr. 01, 2016		Nov. 21, 2014
Number of Equal Vesting Periods			3	1	3	1	1	1	1	1		1	1	1				1	1	3	1	1		1	1	3	1		4	1		1
Executive [Member] \| Restricted Stock [Member] \| Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)															50,000																34,000
Grant Price (in dollars per share)															$ 8.55																$ 5.96
Vesting Date															Feb. 05, 2018																Dec. 31, 2014
Number of Equal Vesting Periods															1																1
Executive [Member] \| Restricted Stock [Member] \| Annual Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)																20,170															90,000
Grant Price (in dollars per share)																$ 7.93															$ 5.96
Vesting Date																Dec. 31, 2015															Feb. 24, 2015
Number of Equal Vesting Periods																1															1