Variable Interest Entities Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Variable Interest Entity [Line Items]
Assets	$ 37,990				$ 16,197				$ 37,990	$ 16,197
Liabilities	31,705				11,818				31,705	11,818
Revenues	1,101	867	836	540	528	515	487	431	3,344	1,960	1,410
Net income	121	161	178	106	91	124	136	112	566	463	386
GERMANY
Variable Interest Entity [Line Items]
Revenues									172
GERMANY | Subsidiaries [Member]
Variable Interest Entity [Line Items]
Assets	3,900								3,900
Liabilities	3,000								3,000
Revenues									172
Net income									$ 30