Revenue From Contracts With Customers (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total interest income	$ 307,208	$ 314,533	$ 292,642	$ 926,300	$ 858,931
Service charges on deposit accounts	3,525	3,771	3,979	11,026	12,418
Other commissions and fees	10,855	11,590	12,397	33,453	34,429
Leased equipment income	9,615	9,182	9,120	28,079	28,497
Gain on sale of loans and leases	765	326	0	1,091	4,675
Gain on sale of securities	908	22,192	826	25,261	7,390
Other income	7,761	3,832	10,590	16,476	27,700
Total noninterest income	33,429	$ 50,893	36,912	115,386	115,109
Revenues	340,637		329,554	1,041,686	974,040
Service charges on deposit accounts	8,918		9,190	26,940	28,278
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	3,525		3,979	11,026	12,418
Other commissions and fees
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	4,965		4,767	14,661	14,519
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	428		444	1,253	1,341
Noninterest Income
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	$ 8,918		$ 9,190	$ 26,940	$ 28,278