Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Variable Interest Entity [Line Items]
Assets	$ 3,108	$ 2,888
Liabilities	2,819	2,567
Weighted average common shares adjustment related to stock-based compensation	2.0	1.9	1.7
Anti-dilutive potential common shares related to stock-based compensation plans	1.0	1.1	1.8
Maturities of short term investments	3 months
New collateralized loan obligation temporary warehousing entities [Member]
Variable Interest Entity [Line Items]
Assets	17
Liabilities	$ 12