Fair Value (Details)	1 Months Ended	3 Months Ended		9 Months Ended		21 Months Ended
	May 31, 2016 USD ($)	Sep. 30, 2016 USD ($) derivative	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) derivative	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) derivative
Derivative instruments and Hedging Activities
Payments for Hedge, Financing Activities				$ 14,847,000	$ 0
Income (loss) on cash flow hedges		$ 719,000	$ (31,000)	(73,826,000)	$ (67,000)
Estimated hedging losses to be reclassified from accumulated other comprehensive loss into earnings within the next twelve months				$ 6,978,000
Cash Flow Hedges
Derivative instruments and Hedging Activities
Number of derivative instruments held | derivative		11		11		11
Interest Rate Cap [Member] | Cash Flow Hedges
Derivative instruments and Hedging Activities
Notional amount		$ 36,108,000		$ 36,108,000		$ 36,108,000
Weighted average interest rate (as a percent)		2.70%		2.70%		2.70%
Weighted average capped interest rate (as a percent)		5.90%		5.90%		5.90%
Interest Rate Swap [Member] | Cash Flow Hedges
Derivative instruments and Hedging Activities
Notional amount		$ 800,000,000		$ 800,000,000		$ 800,000,000
Weighted average capped interest rate (as a percent)		2.30%		2.30%		2.30%
Notional amounts entered into during period				$ 600,000,000		$ 1,200,000,000
Derivative, Notional Amounts Settled During Period	$ 400,000,000
Not Designated as Hedging Instrument [Member]
Derivative instruments and Hedging Activities
Number of derivative instruments held | derivative		15		15		15
Not Designated as Hedging Instrument [Member] | Interest Rate Cap [Member]
Derivative instruments and Hedging Activities
Notional amount		$ 722,943,000		$ 722,943,000		$ 722,943,000
Weighted average interest rate (as a percent)		2.60%		2.60%		2.60%
Weighted average capped interest rate (as a percent)		6.20%		6.20%		6.20%