Revenue From Contracts With Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total interest income	$ 265,908	$ 274,075	$ 307,208	$ 831,315	$ 926,300
Service charges on deposit accounts	2,570	2,004	3,525	7,232	11,026
Other commissions and fees	10,541	10,111	10,855	30,373	33,453
Leased equipment income	9,900	12,037	9,615	34,188	28,079
Gain on sale of loans and leases	35	346	765	468	1,091
Gain on sale of securities	5,270	7,715	908	13,167	25,261
Other income	9,936	6,645	7,761	20,782	16,476
Total noninterest income	38,252	$ 38,858	33,429	106,210	115,386
Revenues	304,160		340,637	937,525	1,041,686
Service charges on deposit accounts	6,087		8,918	18,581	26,940
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	2,570		3,525	7,232	11,026
Other commissions and fees
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	3,228		4,965	10,388	14,661
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	289		428	961	1,253
Noninterest Income
Disaggregation of Revenue [Line Items]
Service charges on deposit accounts	$ 6,087		$ 8,918	$ 18,581	$ 26,940