Time Deposits (Schedule of Detailed Time Deposits) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Banking And Thrift [Abstract]
Noninterest-bearing deposits	$ 8,775,632	$ 8,499,027
Interest-bearing retail transaction and savings deposits	8,845,097	8,000,092
Interest-bearing public fund deposits, Public fund transaction and savings deposits	2,803,912	2,622,938
Interest-bearing public fund deposits, Public fund time deposits	560,503	383,578
Total interest-bearing public fund deposits	3,364,415	3,006,516
Retail time deposits	2,652,842	2,416,086
Brokered time deposits	165,589	1,228,464
Total interest-bearing deposits	15,027,943	14,651,158
Total deposits	$ 23,803,575	$ 23,150,185