Equity Based Compensation Plans (Details)		1 Months Ended	3 Months Ended		12 Months Ended				24 Months Ended
	Dec. 09, 2014 shares	Dec. 31, 2013 shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 09, 2015	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 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		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					5 years
Life of options, maximum					10 years
Accelerated share-based compensation cost			$ 2,700,000
Intrinsic value of the options outstanding and fully vested			29,800,000		$ 29,800,000
Average fair value of stock options granted (in dollars per share) | $ / shares					$ 22.78		$ 20.56	$ 15.80
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
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option grants to officers and employees vesting period					0 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option grants to officers and employees vesting period					5 years
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense					$ 6,100,000		6,100,000	2,300,000
Stock-based compensation capitalized					300,000		400,000	400,000
Intrinsic value of options exercised					19,400,000		$ 12,700,000	$ 3,000,000
Unrecognized compensation cost			3,400,000		$ 3,400,000
Unrecognized compensation cost, weighted average recognition period, minimum					0 years
Unrecognized compensation cost, weighted average recognition period, maximum					5 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost			7,700,000		$ 7,700,000
Unrecognized compensation cost, weighted average recognition period, minimum					0 years
Unrecognized compensation cost, weighted average recognition period, maximum					4 years
Granted (in shares) | shares					56,177		22,014	1,556
2015 LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense				$ 2,400,000
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					10 years
Measurement period					10 years
Unrecognized compensation cost, period for recognition					9 years 6 months
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
Series Z Incentive Units [Member] | Minimum [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%
Series Z Incentive Units [Member] | Maximum [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%
Long Term Incentive Plan 2014 Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage of units per year		25.00%
Conversion ratio, incentive units					1
Liquidity measurement period					10 years
Measurement period					10 years
Vesting percentage for 2011 Z 1 Units to be convertible									100.00%
Unrecognized compensation cost, period for recognition					3 years 2 months 12 days
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					$ 3,500,000		$ 6,000,000	$ 2,200,000
Stock-based compensation capitalized					500,000		$ 400,000	$ 500,000
Unrecognized compensation cost			6,000,000		$ 6,000,000
Granted (in shares) | shares					0		44,750	50,500
Intrinsic value of vested and unvested LTIP units			$ 59,900,000		$ 59,900,000
BRE Properties, Inc. [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense					200,000		$ 3,600,000
Merger and integration expenses					$ 100,000		$ 1,700,000