Certain Transfers of Financial Assets Certain Transfers of Financial Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Outstanding balance:
Beginning balance	$ 1,012,580	$ 980,414
Loans purchased	6,753,709	5,556,964
Payments and loans sold	5,816,504	5,524,798
Ending balance	1,949,785	1,012,580
Fair value adjustment:
Increase/(decrease) to fair value	21,265	9,909
Loans held for sale	1,969,474	1,011,004
Fair value over (under) outstanding balance	19,689	(1,576)	$ 8,333
Small Business Administration Loans [Member]
Fair value adjustment:
Fair value over (under) outstanding balance	$ 299	$ 3,300