Organization and Basis of Presentation - Accumulated Other Comprehensive Loss Summary (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	$ 6,292,237
Balance at period end	6,438,027
Accumulated Other Comprehensive Loss, Net [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	(32,098)
Other comprehensive income before reclassification	9,293
Amounts reclassified from accumulated other comprehensive loss	(5,536)
Other comprehensive income (loss)	3,757
Balance at period end	(28,341)
Change in Fair Value and Amortization of Swap Settlements [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	(32,963)
Other comprehensive income before reclassification	8,629
Amounts reclassified from accumulated other comprehensive loss	(3,972)
Other comprehensive income (loss)	4,657
Balance at period end	(28,306)
Unrealized Gains/(Loss) on Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	865
Other comprehensive income before reclassification	664
Amounts reclassified from accumulated other comprehensive loss	(1,564)
Other comprehensive income (loss)	(900)
Balance at period end	$ (35)