Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Computation of basic and diluted earnings per share
Numerator for basic and diluted earnings per share - net income attributable to common stockholders	$ 163,729	$ 325,585	$ 179,246	$ 310,284	$ 224,324	$ 589,876	$ 137,762	$ 280,470	$ 978,844		$ 1,232,432		$ 758,250
Adjustment for net income (loss) attributable to OP units									(6,146)		806		173
Numerator for diluted earnings per share									$ 972,698		$ 1,233,238		$ 758,423
Denominator for basic earnings per share - weighted average shares (in shares)									415,451,000		401,845,000		373,620,000
Effect of dilutive securities:
Employee stock options (in shares)									0		0		9,000
Non-vested restricted shares (in shares)									519,000		835,000		512,000
Redeemable shares (in shares)									1,396,000		1,112,000		1,096,000
Employee stock purchase program (in shares)									21,000		16,000		13,000
Dilutive potential common shares (in shares)									1,936,000		1,963,000		1,630,000
Denominator for diluted earnings per share - adjusted weighted average shares (in shares)									417,387,000		403,808,000		375,250,000
Basic earnings per share (in USD per share)	$ 0.39	$ 0.78	$ 0.43	$ 0.76	$ 0.55	$ 1.46	$ 0.34	$ 0.72	$ 2.36		$ 3.07		$ 2.03
Diluted earnings per share (in USD per share)	$ 0.39	$ 0.77	$ 0.42	$ 0.75	$ 0.55	$ 1.45	$ 0.34	$ 0.71	$ 2.33	[1]	$ 3.05	[1]	$ 2.02	[1]
Stock Option
Effect of dilutive securities:
Number of shares not included in the computation of diluted earnings per share because such options were anti-dilutive (in shares)											4,935,804

[1] Includes adjustment to the numerator for income (loss) attributable to OP unitholders