Revenue From Contracts With Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total interest income	$ 274,075	$ 291,332	$ 314,533	$ 565,407	$ 619,092
Service charges on deposit accounts	2,004	2,658	3,771	4,662	7,501
Other commissions and fees	10,111	9,721	11,590	19,832	22,598
Leased equipment income	12,037	12,251	9,182	24,288	18,464
Gain on sale of loans and leases	346	87	326	433	326
Gain on sale of securities	7,715	182	22,192	7,897	24,353
Other income	6,645	4,201	3,832	10,846	8,715
Total noninterest income	38,858	$ 29,100	50,893	67,958	81,957
Revenues	312,933		365,426	633,365	701,049
Service charges on deposit accounts	5,346		9,383	12,494	18,022
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	2,004		3,771	4,662	7,501
Other commissions and fees
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	3,006		5,158	7,160	9,696
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	336		454	672	825
Noninterest Income
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	$ 5,346		$ 9,383	$ 12,494	$ 18,022