Derivative Instruments and Hedging Activities - Other Derivative Instruments (Details) - Other Derivative Instruments - USD ($) $ in Thousands		Jun. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Gross notional amount outstanding		$ 3,289,412	$ 3,085,226
Derivative asset fair value in other assets	[1]	57,897	25,168
Derivative liability fair value in other liabilities	[1]	(21,372)	(17,533)
Fair value of derivative	[2]	$ 21,494	$ 18,013

[1] Certain other derivative instruments are centrally cleared and their change in fair value is settled by the counterparties to the transaction, which results in no fair value.

[2] This amount represents the fair value if credit risk related contingent features were triggered.