Derivative Instruments and Balance Sheet Offsetting - Balance Sheet Offsetting (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Offsetting derivative assets
Gross amounts recognized	$ 14,713	$ 8,215
Offsetting derivative liabilities
Gross amounts recognized	11,739	6,359
Interest rate swaps and customer-initiated derivatives
Offsetting derivative assets
Gross amounts recognized	9,932	4,405
Gross amounts offset in the statements of financial condition	0	0
Net amounts presented in the statements of financial position	9,932	4,405
Gross amounts not offset in the statements of financial position
Financial instruments	0	0
Collateral (received)/posted	0	0
Net Amount	9,932	4,405
Offsetting derivative liabilities
Gross amounts recognized	9,438	4,141
Gross amounts offset in the statements of financial condition	0	0
Net amounts presented in the statements of financial position	9,438	4,141
Gross amounts not offset in the statements of financial position
Financial instruments	0	0
Collateral (received)/posted	7,161	2,550
Net Amount	$ 2,277	$ 1,591