Derivative Instruments and Hedging Activities - Cash Flow Hedge Accounting on AOCI (Details) - Cash Flow Hedging - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest Income
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (losses) recognized in other comprehensive income	$ 2,578	$ 113	$ 13,151	$ 5,465
Reclassification of gains (losses) included in net income	857	946	1,504	4,333
Interest Expense
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (losses) recognized in other comprehensive income	(1,577)	(416)	(11,620)	(3,807)
Reclassification of gains (losses) included in net income	$ (978)	$ (919)	$ (2,087)	$ (3,142)