Accounting Policies (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Assets	$ 4,047	$ 3,108
Liabilities	$ 3,781	$ 2,819
Weighted average common shares adjustment related to stock-based compensation	1.8	2.0	1.9
Anti-dilutive potential common shares related to stock-based compensation plans	1.1	1.0	1.1
Maturities of short term investments	3 months
New collateralized loan obligation temporary warehousing entities [Member]
Variable Interest Entity [Line Items]
Assets	$ 100
Liabilities	$ 80