Commitments and Contingencies (Details Textual) (USD $)	1 Months Ended	12 Months Ended	0 Months Ended		1 Months Ended			0 Months Ended
	Dec. 31, 2003	Dec. 31, 2014	Feb. 03, 2015	Jan. 21, 2015	Jul. 31, 2014 analysts	Dec. 31, 2012	Jun. 30, 2011	Jan. 15, 2014	Dec. 31, 2013	Oct. 31, 2005
Loss Contingencies [Line Items]
Sale of equity investment in Rock-McGraw, Inc., percentage	45.00%
Percentage of leased building space, company		17.00%
Proceeds from the disposition of equity investment in Rock-McGraw	$ 382,000,000
Pre-tax gain from Sale of equity investment in Rock-McGraw	131,000,000
After-tax gain from Sale of equity investment in Rock-McGraw	58,000,000
Pre-tax gain pursuant to sale-leaseback accounting rules	212,000,000
After-tax gain pursuant to sale-leaseback accounting rules	126,000,000
Deferred gain		7,000,000							60,000,000
Gain amortized during year		21,000,000
Accelerated recognition of deferred gain		16,000,000
Interest expense with operating lease		2,000,000
Financial Crisis Litigation [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Damages awarded			687,500,000
Financial Crisis Litigation [Member] | Arizona, Arkansas, California, Connecticut, Colorado, Delaware, Idaho, Illinois, Indiana, Iowa, Maine, Mississippi, Missouri, New Jersey, North Carolina, Pennsylvania, South Carolina, Tennessee and Washington, and the District of Columbia | Subsequent Event [Member]
Loss Contingencies [Line Items]
Damages awarded			687,500,000
Financial Crisis Litigation [Member] | California | Subsequent Event [Member]
Loss Contingencies [Line Items]
Damages awarded			125,000,000
U.S. Securities and Exchange Commission [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Penalties awarded				58,000,000
Disgorgement and prejudgement interest paid				7,000,000
U.S. Securities and Exchange Commission [Member] | New York and the Commonwealth of Massachusetts [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Damages awarded				19,000,000
Parmalat [Member]
Loss Contingencies [Line Items]
Damages claimed										4,100,000,000
Rating fees paid						1,100,000	800,000
Number of analysts served notice of completion					8
Italian Administrative Court [Member]
Loss Contingencies [Line Items]
Damages sought								$ 234,000,000,000