Stockholders' Equity 2 (Details) (USD $) Share data in Millions, unless otherwise specified	1 Months Ended	6 Months Ended
	May 31, 2014	Sep. 30, 2014	Mar. 31, 2014
Equity [Abstract]
Stock repurchase program, Authorized amount	$ 1,000,000,000
Shares of common stock repurchased		1.7
Value of common stock repurchased		50,000,000
Remaining authorized common stock repurchase amount		950,000,000
Accumulated other comprehensive loss		$ (255,000,000)	$ (171,000,000)