Accumulated Other Comprehensive Income - Impact of Reclassifications out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income
Interest expense	$ (56,520)	$ (50,534)
Interest income from investment securities	19,403	27,744
Net income	27,046	120,779
Amounts Reclassified from AOCI
Accumulated Other Comprehensive Income
Net income	(95)	5,192
Effective Portion of Cumulative Loss on Cash Flow Hedges | Interest rate contracts | Amounts Reclassified from AOCI
Accumulated Other Comprehensive Income
Interest expense	$ (95)	(204)
Cumulative Unrealized Gain (Loss) on Available-for-Sale Securities | Amounts Reclassified from AOCI
Accumulated Other Comprehensive Income
Interest income from investment securities		$ 5,396