Deposits (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Demand and other noninterest-bearing		$ 5,227,216	$ 5,081,901
Interest-bearing demand		1,244,254	1,265,212
Money market		2,367,964	2,543,712
Savings		890,557	861,941
Certificates of deposit less than $250,000		243,849	286,791
Total core deposits		9,973,840	10,039,557
Certificates of deposit greater than $250,000		89,473	100,399
Certificates of deposit insured by CDARS®	[1]	23,580	25,374
Brokered certificates of deposit		57,930	78,481
Reciprocal money market accounts	[1]	313,692	289,031
Subtotal		10,458,515	10,532,842
Deposits, Valuation Adjustment From Acquisition Accounting		(389)	(757)
Total deposits		10,458,126	10,532,085
Deposit Liabilities Reclassified as Loans Receivable		4,000	$ 1,600
Time Deposits, Fiscal Year Maturity [Abstract]
2019		292,334
2020		71,405
2021		23,604
2022		12,761
2023		10,820
Thereafter		3,908
Total		$ 414,832

[1] (1) For periods prior to June 30, 2018, CDARS and reciprocal money market accounts were considered to be brokered deposits by regulatory authorities and were reported as such on quarterly Call Reports. With the passage of the The Economic Growth, Regulatory Relief and Consumer Protection Act in May 2018, these items are no longer considered brokered deposits.