Segment Information - Schedule of Financial Information of Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Investment in unconsolidated real estate ventures	$ 79,570				$ 103,007				$ 79,570	$ 103,007
Total assets	7,091,446				6,071,407				7,091,446	6,071,407
Total revenues	261,016	$ 257,183	$ 244,273	$ 229,403	225,759	$ 197,497	$ 185,860	$ 173,154	991,875	782,270	$ 647,155
Operating expenses, including depreciation and amortization	137,832	134,459	133,971	135,775	185,450	100,193	104,253	97,718	542,037	487,614	368,687
Income (loss) from operations	123,184	122,724	110,302	93,628	40,309	97,304	81,607	75,436	449,838	294,656	278,468
Gain (loss) on real estate transactions, earnout from prior acquisition and sale of other assets									8,465	1,501	(10,285)
Property casualty loss, net									0	0	(1,724)
Interest expense									(133,479)	(95,682)	(81,330)
Non-cash interest expense related to the amortization of discount on equity component of exchangeable senior notes									(4,980)	(3,310)	(2,683)
Interest income									6,148	3,461	1,607
Interest income on note receivable from Preferred Operating Partnership unit holder									4,850	4,850	4,850
Equity in earnings of unconsolidated real estate ventures									12,895	12,351	10,541
Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of partners' interests									(69,199)	(2,857)	(4,022)
Income tax (expense) benefit									(15,847)	(11,148)	(7,570)
Net income (loss)	90,416	$ 127,226	$ 90,040	$ 89,407	11,744	$ 78,200	$ 60,956	$ 58,636	397,089	209,536	195,896
Depreciation and amortization expense									182,560	133,457	115,076
Acquisition of real estate assets									(1,086,523)	(349,897)	(503,538)
Development and redevelopment of real estate assets									(23,279)	(26,931)	(23,528)
Rental Operations [Member]
Segment Reporting Information [Line Items]
Investment in unconsolidated real estate ventures	79,570				103,007				79,570	103,007
Total assets	6,731,292				5,674,030				6,731,292	5,674,030
Total revenues									864,742	676,138	559,868
Operating expenses, including depreciation and amortization									423,575	328,380	279,497
Income (loss) from operations									441,167	347,758	280,371
Interest expense									(129,907)	(93,711)	(80,160)
Equity in earnings of unconsolidated real estate ventures									12,895	12,351	10,541
Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of partners' interests											4,022
Income tax (expense) benefit									(2,320)	(1,729)	(1,157)
Net income (loss)									321,835	264,669	207,871
Depreciation and amortization expense									173,570	124,415	107,081
Tenant Reinsurance [Member]
Segment Reporting Information [Line Items]
Total assets	44,524				37,696				44,524	37,696
Total revenues									87,291	71,971	59,072
Operating expenses, including depreciation and amortization									15,555	13,033	10,427
Income (loss) from operations									71,736	58,938	48,645
Income tax (expense) benefit									(12,610)	(9,780)	(8,662)
Net income (loss)									59,138	49,173	40,000
Property Management Acquisition and Development [Member]
Segment Reporting Information [Line Items]
Total assets	$ 315,630				$ 359,681				315,630	359,681
Total revenues									39,842	34,161	28,215
Operating expenses, including depreciation and amortization									102,907	146,201	78,763
Income (loss) from operations									(63,065)	(112,040)	(50,548)
Gain (loss) on real estate transactions, earnout from prior acquisition and sale of other assets									8,465	1,501	(10,285)
Property casualty loss, net									0	0
Interest expense									(3,572)	(1,971)	(1,170)
Non-cash interest expense related to the amortization of discount on equity component of exchangeable senior notes									4,980	3,310	2,683
Interest income									6,148	3,461	1,607
Interest income on note receivable from Preferred Operating Partnership unit holder									4,850	4,850	4,850
Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of partners' interests									(69,199)	(2,857)	(4,022)
Income tax (expense) benefit									(917)	361	2,249
Net income (loss)									16,116	(104,306)	(51,975)
Depreciation and amortization expense									8,990	9,042	7,995
Acquisition of real estate assets									(1,086,523)	(1,550,750)	(503,538)
Development and redevelopment of real estate assets									$ (23,279)	$ (26,931)	$ (23,528)