Deposits - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deposits [Abstract]
Deposits	$ 18,943,158	$ 15,505,383
Brokered deposits	10,300,000	8,200,000
Retail and other deposits	8,600,000	7,300,000
Aggregate of deposits of individual depositors	5,900,000	5,500,000
Brokered deposit placement fee	13,000	9,000	$ 10,000
Third party broker fees paid	26,000	12,000	$ 4,000
Deposits exceeding FDIC insurance limits	523,000	396,000
Accrued interest on deposits	$ 53,000	$ 28,000