Income Taxes Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Abstract]
Allowance for loan and OREO losses	$ 22,782	$ 35,545
Interest on nonaccrual loans	295	548
Stock compensation	3,156	6,079
Deferred and accrued compensation	11,822	19,801
Contingent payments	1,236	1,868
Unrealized loss on investments	3,345	8,264
Other	1,437	905
Gross deferred tax assets	44,073	73,010
Total deferred tax assets	44,073	73,010
Deferred income on repurchase of debt	832	2,692
Goodwill and acquired intangible assets	12,246	12,929
Fixed assets	991	67
Prepaid expenses	347	611
Other	626	1,251
Total gross deferred tax liabilities	15,042	17,550
Net deferred tax asset	$ 29,031	$ 55,460