Summary of Significant Accounting Policies - Reclassifications out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Accounting Policies
Interest expense									$ (923,697)	$ (992,601)	$ (1,082,081)
Other income									325,597	200,781	168,035
Net income attributable to noncontrolling interests									(311,655)	(242,938)	(231,949)
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS	$ 392,297	$ 420,009	$ 472,944	$ 539,134	$ 405,048	$ 251,968	$ 406,587	$ 341,648	1,824,383	1,405,251	1,316,304
Accumulated Net Gain (Loss) from Derivatives Including Portion Attributable to Noncontrolling Interest | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Interest expense									(10,998)	(10,789)	(9,205)
Accumulated Net Gain (Loss) from Derivatives Attributable to Noncontrolling Interest | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Net income attributable to noncontrolling interests									1,577	1,568	1,317
Accumulated derivative losses, net | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS									(9,421)	$ (9,221)	$ (7,888)
Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Other income									80,187
Accumulated Net Investment Gain (Loss) Attributable to Noncontrolling Interest | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Net income attributable to noncontrolling interests									(11,502)
Net gains on marketable securities | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS									$ 68,685