Derivatives and other Hedging Instruments - Additional Information (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) Contract	Dec. 31, 2014 Contract	Dec. 31, 2013 Contract
Derivative [Line Items]
Estimated amount related to derivatives reclassified to interest expense during the next 12 months	$ 1,864,000
Early Terminated Interest Rate Swaps
Derivative [Line Items]
Notional Amount	1,400,000,000
Payment on termination of interest rate swaps	$ 5,210,000
Derivative, Maturity Date	Dec. 31, 2015
Interest Rate Swaptions
Derivative [Line Items]
Number of derivative instruments outstanding | Contract	6	4
Proceeds from swaptions termination	$ 2,049,000
Eurodollar Future
Derivative [Line Items]
Notional Amount	$ 1,000,000
Number of derivative instruments outstanding | Contract	108,824	130,074	95,327
Derivative term of contract	3 months
Futures contracts range	2015 through 2021
Fair value of derivatives in net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, related to agreements	$ 6,802,000