Long-term Funding (Textual) (Details) - USD ($) $ in Millions	1 Months Ended
	Nov. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2011	Mar. 31, 2011
Subordinated Borrowing [Line Items]
Federal Home Loan Bank, Advances, Weighted Average Interest Rate		0.50%	0.23%
Long-term Federal Home Loan Bank Advances		$ 6,000
Federal Home Loan Bank Advances		$ 2,700
Two Thousand Eleven Senior Notes [Member]
Subordinated Borrowing [Line Items]
New Senior Debt Issued				$ 130	$ 300
Debt Instrument, Interest Rate, Stated Percentage					5.125%
Two Thousand Fourteen Senior Notes [Member]
Subordinated Borrowing [Line Items]
New Senior Debt Issued	$ 250
Debt Instrument, Interest Rate, Stated Percentage	2.75%
Two Thousand Fourteen Subordinated Notes [Member]
Subordinated Borrowing [Line Items]
Junior Subordinated Debentures Issued	$ 250
Debt Instrument, Term	10 years
Subordinated Borrowing, Interest Rate	4.25%