Deposits - Certificates of Deposits Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Time Deposits, Fiscal Year Maturity [Abstract]
One year or less	$ 4,098,520	$ 3,716,183
After one year to two years	2,045,861	1,550,130
After two years to three years	1,479,292	806,488
After three years to four years	494,654	447,592
After four years to five years	1,274,198	445,884
After five years	159,449	67,844
Total	$ 9,551,974	$ 7,034,121