Derivatives and Hedging - Cash Flow Hedges (Details) - Derivatives designated as hedging instrument - Cash flow hedges - Interest Rate Swap - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Cash flow hedges not terminated, net fair value	$ (2,000)
Fair value hedges weighted average expected remaining term	5 months 16 days
Gain (loss) on discontinuation of interest rate cash flow hedge due to forecasted transaction probable of not occurring, net	$ 0	$ 0
Cash flow hedge gain (loss) to be reclassified within twelve months	$ (38,500)
Maximum length of time hedged in interest rate cash flow hedge	3 years 3 months 30 days
Interest rate and foreign currency exchange contracts:
Net change in amount recognized in other comprehensive income	$ (237)	(9,866)
Amount reclassified from accumulated other comprehensive income (loss) into net income	(9,385)	5,694
Amount of ineffectiveness recognized in net income	$ 30	$ (749)