Revenue From Contracts With Customers (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Total interest income	$ 314,533	$ 304,559	$ 288,514	$ 619,092	$ 566,289
Service charges on deposit accounts	3,771	3,730	4,265	7,501	8,439
Other commissions and fees	11,590	11,008	11,767	22,598	22,032
Leased equipment income	9,182	9,282	9,790	18,464	19,377
Gain on sale of loans and leases	326	0	106	326	4,675
Gain on sale of securities	22,192	2,161	253	24,353	6,564
Other income	3,832	4,883	13,457	8,715	17,110
Total noninterest income	50,893	$ 31,064	39,638	81,957	78,197
Revenues	365,426		328,152	701,049	644,486
Service charges on deposit accounts	9,383		9,802	18,022	19,088
Interest Income
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	0		0	0	0
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	3,771		4,265	7,501	8,439
Other commissions and fees
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	5,158		5,101	9,696	9,752
Leased equipment income
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	0		0	0	0
Gain on sale of loans
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	0		0	0	0
Gain on sale of securities
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	0		0	0	0
Other income
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	454		436	825	897
Noninterest Income
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	$ 9,383		$ 9,802	$ 18,022	$ 19,088