Derivative Instruments and Hedging Activities - Offsetting Derivatives (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Assets
Gross amounts recognized		$ 32,057	$ 21,068
Less: amounts offset in the Consolidated Statements of Financial Condition		0	0
Net amount presented in the Consolidated Statements of Financial Condition	[1]	32,057	21,068
Offsetting derivative positions		(11,678)	(16,880)
Cash collateral pledged		(9,060)	0
Net credit exposure		11,319	4,188
Liabilities
Gross amounts recognized		28,861	25,250
Less: amounts offset in the Consolidated Statements of Financial Condition		0	0
Net amount presented in the Consolidated Statements of Financial Condition	[1]	28,861	25,250
Offsetting derivative positions		(11,678)	(16,880)
Cash collateral pledged		(3,506)	(8,370)
Net credit exposure		$ 13,677	$ 0

[1] Included in other assets or other liabilities in the Consolidated Statements of Financial Condition.