Organization and Basis of Presentation - Accumulated Other Comprehensive Loss Summary (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 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	6,436,028
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	17,991
Amounts reclassified from accumulated other comprehensive loss	(5,859)
Other comprehensive income	9,898
Balance at period end	(8,548)
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	18,075
Amounts reclassified from accumulated other comprehensive loss	(5,865)
Other comprehensive income	12,210
Balance at period end	(8,431)
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	(84)
Amounts reclassified from accumulated other comprehensive loss	6
Other comprehensive income	(2,312)
Balance at period end	$ (117)