Other Borrowings - FHLB Advances - (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
FHLB Advances
Outstanding advances	$ 123,000	$ 130,000
FHLB Advances
FHLB Advances
Loans pledged via a blanket lien to the FHLB for advances and letters of credit	2,600,000,000
Total borrowing capacity at FHLB	1,300,000,000
Letter of credit borrowed	5,700,000
Unused net credit available with the FHLB	$ 1,300,000,000