Revenue from Contracts with Customers (Revenue from Contracts with Customers) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Residential mortgage banking revenue, net									$ 270,822	$ 101,810	$ 118,235
Gain (loss) on sale of debt securities, net									190	(7,184)	14
Gain (loss) on equity securities, net									769	83,475	(1,484)
Gain on loan and lease sales, net									6,707	10,467	7,834
BOLI income									8,399	8,406	8,297
Remaining other income									40,495	48,306	55,960
Other income									50,962	62,459	67,917
Total non-interest income	$ 123,960	$ 131,924	$ 115,480	$ 40,645	$ 83,749	$ 88,512	$ 121,823	$ 45,740	412,009	339,824	279,417
Account Service Fees
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer									22,497	20,672	17,378
Transaction-based and overdraft service charges
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer									18,341	24,944	25,636
Debit/ATM Interchange Fees
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer									17,723	18,898	19,110
Service charges on deposits
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer									58,561	64,514	62,124
Brokerage revenue
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer									15,599	15,877	16,480
Merchant Fee Income
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer									3,200	5,207	4,565
Credit Card and Interchange Income
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer									$ 7,267	$ 8,946	$ 7,392