Divestitures (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 31, 2011	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Divestitures and Assets Held for Sale [Abstract]
Purchase price for divestiture of business/controlling interest	$ 1,500
Proceeds from business divestitures, net of costs		0	12	30	10	1,450
Segment Reporting, Sales from Divested Businesses		0	2
Gain on divestiture		$ 0	$ (12)