Loans and Allowance - Changes in Allowance for Loan Losses by Loan Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Allowance for loan losses:
Beginning balance	$ 62,186	$ 62,550	$ 62,453	$ 63,964
Provision for losses	1,900		3,240	417
Recoveries on loans	1,251	2,371	4,224	4,875
Loans charged off	(1,881)	(2,060)	(6,461)	(6,395)
Ending balance	63,456	62,861	63,456	62,861
Commercial
Allowance for loan losses:
Beginning balance	26,321	31,479	26,478	28,824
Provision for losses	727	3,202	1,266	6,226
Recoveries on loans	175	281	1,150	1,168
Loans charged off	(720)	(1,026)	(2,391)	(2,282)
Ending balance	26,503	33,936	26,503	33,936
Commercial Real Estate
Allowance for loan losses:
Beginning balance	22,280	15,828	22,145	19,327
Provision for losses	578	(2,966)	992	(6,364)
Recoveries on loans	651	1,510	1,879	2,069
Loans charged off	(572)	(386)	(2,079)	(1,046)
Ending balance	22,937	13,986	22,937	13,986
Consumer
Allowance for loan losses:
Beginning balance	2,684	2,927	2,689	2,658
Provision for losses	115	(102)	192	225
Recoveries on loans	101	67	286	246
Loans charged off	(114)	(169)	(381)	(406)
Ending balance	2,786	2,723	2,786	2,723
Residential
Allowance for loan losses:
Beginning balance	10,899	12,311	11,139	13,152
Provision for losses	480	(132)	790	330
Recoveries on loans	324	513	909	1,392
Loans charged off	(475)	(479)	(1,610)	(2,661)
Ending balance	11,228	12,213	11,228	12,213
Finance Leases
Allowance for loan losses:
Beginning balance	2	5	2	3
Provision for losses		(2)
Recoveries on loans
Loans charged off
Ending balance	$ 2	$ 3	$ 2	$ 3