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Equity Based Compensation Plans (Details) |  | 1 Months Ended | 12 Months Ended | 24 Months Ended
--- | --- | --- | --- | ---
Dec. 09, 2014 shares | Dec. 31, 2013 shares | Dec. 31, 2016 USD ($) $ / shares shares | Dec. 31, 2015 USD ($) $ / shares shares | Dec. 09, 2015 | Dec. 31, 2014 USD ($) $ / shares shares | Dec. 31, 2011 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Number of shares available (in shares) | shares |  |  | 1,000,000 |  |  |  |
Exercise price as a percentage of fair market value of common stock on grant date, minimum (in hundredths) |  |  | 100.00% |  |  |  |
Life of options, minimum (in years) |  |  | 5 years |  |  |  |
Life of options, maximum (in years) |  |  | 10 years |  |  |  |
Accelerated share-based compensation cost |  |  | $ 3,500,000 | $ 2,700,000 |  |  |
Intrinsic value of the options outstanding and fully vested |  |  | $ 20,800,000 | $ 29,800,000 |  |  |
Average fair value of stock options granted (in dollars per share) | $ / shares |  |  | $ 21.65 | $ 22.78 |  | $ 20.56 |
Cap on the appreciation of the market price over the exercise price, option 1 |  |  | $ 75 | $ 75 |  | $ 75 |
Cap on the appreciation of the market price over the exercise price, option 2 |  |  | 100 | 100 |  | 100 |
Cap on the appreciation of the market price over the exercise price, option 3 |  |  | 125 | 125 |  | 125 |
BRE Properties, Inc. [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Share based compensation expense |  |  | 100,000 | 200,000 |  |  |
Merger and integration expenses |  |  | 0 | 100,000 |  | 1,700,000 |
Stock Options [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Share based compensation expense |  |  | 8,200,000 | 6,100,000 |  | 6,100,000 |
Stock-based compensation capitalized |  |  | 500,000 | 300,000 |  | 400,000 |
Intrinsic value of options exercised |  |  | 11,900,000 | $ 19,400,000 |  | $ 12,700,000 |
Unrecognized compensation cost |  |  | $ 5,000,000 |  |  |  |
Unrecognized compensation cost, period for recognition (in years) |  |  | 2 years 9 months 15 days |  |  |  |
Restricted Stock [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Unrecognized compensation cost |  |  | $ 5,900,000 |  |  |  |
Unrecognized compensation cost, period for recognition (in years) |  |  | 2 years 2 months 12 days |  |  |  |
Granted (in shares) | shares |  |  | 49,183 | 56,177 |  | 22,014 |
2015 LTIP Units [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Option grants to officers and employees vesting period | 5 years |  |  |  |  |  |
Share based compensation expense |  |  |  |  |  | $ 2,400,000 |
Unrecognized compensation cost, period for recognition (in years) |  |  | 8 years 6 months |  |  |  |
Granted (in shares) | shares | 44,750 |  |  |  |  |  |
Units issued subject only to performance measurement | shares | 24,000 |  |  |  |  |  |
Vesting percentage of units per year | 20.00% |  |  |  |  |  |
Percent of awards earned |  |  |  |  | 95.75% |  |
Conversion ratio, incentive units |  |  | 1 |  |  |  |
Liquidity measurement period (in years) |  |  | 10 years |  |  |  |
Measurement period (in years) |  |  | 10 years |  |  |  |
Series Z Incentive Units [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Option grants to officers and employees vesting period |  | 4 years |  |  |  |  |
Granted (in shares) | shares |  | 50,500 |  |  |  |  | 154,500
Conversion ratio, incentive units |  |  |  |  |  |  | 1
Incentive units conversion ratio |  |  |  |  |  |  | one-for-one
Long Term Incentive Plan 2014 Units [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Unrecognized compensation cost, period for recognition (in years) |  |  | 2 years 2 months 12 days |  |  |  |
Vesting percentage of units per year |  | 25.00% |  |  |  |  |
Conversion ratio, incentive units |  |  | 1 |  |  |  |
Liquidity measurement period (in years) |  |  | 10 years |  |  |  |
Measurement period (in years) |  |  | 10 years |  |  |  |
Vesting percentage for 2011 Z 1 Units to be convertible |  |  |  |  |  |  | 100.00%
Long Term Incentive Plans - Z Units and 2014 LTIP Units [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Share based compensation expense |  |  | $ 2,700,000 | $ 3,500,000 |  | 6,000,000 |
Stock-based compensation capitalized |  |  | 600,000 | $ 500,000 |  | $ 400,000 |
Unrecognized compensation cost |  |  | $ 3,600,000 |  |  |  |
Granted (in shares) | shares |  |  | 0 | 0 |  | 44,750 |
Intrinsic value of vested and unvested LTIP units |  |  | $ 56,000,000 |  |  |  |
Minimum [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Option grants to officers and employees vesting period |  |  | 0 years |  |  |  |
Minimum [Member] | Series Z Incentive Units [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Option grants to officers and employees vesting period |  |  | 8 years |  |  |  |
Vesting percentage of units per year |  |  |  |  |  |  | 0.00%
Maximum [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Option grants to officers and employees vesting period |  |  | 5 years |  |  |  |
Maximum [Member] | Series Z Incentive Units [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Option grants to officers and employees vesting period |  |  | 15 years |  |  |  |
Vesting percentage of units per year |  |  |  |  |  |  | 14.00%

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