Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Abstract]
Allowance for loan losses	$ 51,517	$ 89,120
Employee compensation and benefits	9,783	28,401
Loan purchase accounting adjustments	6,441	12,047
Tax credit carryforward	21,274	29,085
Securities	12,250	23,169
State net operating loss	1,979	1,690
Other	15,407	14,583
Gross deferred tax assets	118,651	198,095
State valuation allowance	(1,979)	(1,690)
Subtotal valuation allowance	(1,979)	(1,690)
Net deferred tax assets	116,672	196,405
Fixed assets & intangibles	(56,526)	(74,518)
FDIC indemnification asset		(6,293)
Other	(6,167)	(11,159)
Gross deferred tax liabilities	(62,693)	(91,970)
Net deferred tax asset	$ 53,979	$ 104,435