Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Abstract]
Cash and due from banks	$ 6,492,443	$ 3,444,971
Securities purchased under agreements to resell	289,340	123,611
Other short-term investment securities	0	2,957
Total cash and cash equivalents	$ 6,781,783	$ 3,571,539	$ 2,923,075	$ 2,545,750