Derivative Instruments and Balance Sheet Offsetting - Balance Sheet Offsetting (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Offsetting derivative assets
Gross amounts recognized	$ 73,068	$ 38,595
Offsetting derivative liabilities
Gross amounts recognized	97,179	32,379
Interest rate swaps and customer-initiated derivatives
Offsetting derivative assets
Gross amounts recognized	69,553	36,791
Gross amounts offset in the statements of financial condition	0	0
Net amounts presented in the statements of financial position	69,553	36,791
Gross amounts not offset in the statements of financial position
Financial instruments	0	0
Collateral (received)/posted	0	(16,120)
Net Amount	69,553	20,671
Offsetting derivative liabilities
Gross amounts recognized	95,492	30,822
Gross amounts offset in the statements of financial condition	0	0
Net amounts presented in the statements of financial position	95,492	30,822
Gross amounts not offset in the statements of financial position
Financial instruments	0	0
Collateral (received)/posted	37,291	430
Net Amount	$ 58,201	$ 30,392