Subsequent Event (Details) (USD $) In Billions, except Per Share data, unless otherwise specified	3 Months Ended			6 Months Ended		0 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Sep. 30, 2012	Jun. 30, 2014	Jun. 30, 2013	Aug. 06, 2014 Subsequent event
Subsequent events
Share repurchase authorized			$ 3.0			$ 1.0
Cash dividend declared (in dollars per share)	$ 1.00	$ 0.40		$ 2.00	$ 0.80	$ 1.50
Increase in quarterly cash dividend (as a percent)						50.00%
Prior quarterly cash dividend declared (in dollars per share)	$ 1.00