Organization and Basis of Presentation - Accumulated Other Comprehensive Loss Summary (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	$ 6,396,825
Balance at period end	6,474,683
Accumulated Other Comprehensive Loss, Net [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	(18,446)
Cumulative effect upon adoption		$ (2,234)
Other comprehensive income before reclassification	13,168
Amounts reclassified from accumulated other comprehensive loss	(3,926)
Other comprehensive income	7,008
Balance at period end	(11,438)
Change in Fair Value and Amortization of Swap Settlements [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	(20,641)
Cumulative effect upon adoption		0
Other comprehensive income before reclassification	13,263
Amounts reclassified from accumulated other comprehensive loss	(3,928)
Other comprehensive income	9,335
Balance at period end	(11,306)
Unrealized Gains/(Loss) on Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	2,195
Cumulative effect upon adoption		$ (2,234)
Other comprehensive income before reclassification	(95)
Amounts reclassified from accumulated other comprehensive loss	2
Other comprehensive income	(2,327)
Balance at period end	$ (132)