Stockholders' Equity 1 (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Cash dividends
Declaration date	Feb. 05, 2014	Nov. 06, 2013	Aug. 01, 2013	May 09, 2013	Feb. 07, 2013	Nov. 07, 2012	Aug. 02, 2012	May 08, 2012
Dividend per share (in dollars per share)	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25
Record date	Feb. 20, 2014	Nov. 21, 2013	Aug. 22, 2013	May 23, 2013	Feb. 21, 2013	Nov. 20, 2012	Aug. 14, 2012	May 22, 2012
Total amount	$ 112	$ 113	$ 114	$ 114	$ 114	$ 114	$ 116	$ 119	$ 453	$ 463	$ 192
Payment date	Mar. 18, 2014	Dec. 10, 2013	Sep. 10, 2013	Jun. 11, 2013	Mar. 19, 2013	Dec. 11, 2012	Sep. 11, 2012	Jun. 12, 2012

Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

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