Stock Compensation (Details) In Millions, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended					3 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended				12 Months Ended				1 Months Ended						5 Months Ended	12 Months Ended				12 Months Ended					12 Months Ended
	May 31, 2012 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2012	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2012 Long Term Incentive Plan [Member] USD ($)	Mar. 29, 2012 Short Term Incentive Plan [Member] USD ($)	Dec. 31, 2012 Short Term Incentive Plan [Member] USD ($)	Dec. 31, 2011 Short Term Incentive Plan [Member] USD ($)	Dec. 31, 2010 Short Term Incentive Plan [Member] USD ($)	Dec. 31, 2009 Short Term Incentive Plan [Member] USD ($)	May 31, 2012 Director Stock Plan [Member]	Dec. 31, 2012 Director Stock Plan [Member] USD ($)	Dec. 31, 2011 Director Stock Plan [Member] USD ($)	Dec. 31, 2010 Director Stock Plan [Member] USD ($)	Dec. 31, 2009 Director Stock Plan [Member] USD ($)	Dec. 31, 2012 Executive Incentive Plan [Member] USD ($)	Dec. 31, 2011 Executive Incentive Plan [Member] USD ($)	Dec. 31, 2010 Executive Incentive Plan [Member] USD ($)	Dec. 31, 2009 Executive Incentive Plan [Member] USD ($)	Nov. 30, 2012 Class A [Member] Long Term Incentive Plan [Member] USD ($)	Aug. 31, 2012 Class A [Member] Long Term Incentive Plan [Member] USD ($)	May 31, 2012 Class A [Member] Long Term Incentive Plan [Member] USD ($)	Jan. 31, 2012 Class A [Member] Long Term Incentive Plan [Member] USD ($)	May 31, 2011 Class A [Member] Long Term Incentive Plan [Member] USD ($)	Feb. 28, 2011 Class A [Member] Long Term Incentive Plan [Member] USD ($)	May 31, 2009 Class A [Member] Long Term Incentive Plan [Member] USD ($)	Dec. 31, 2012 Class A [Member] Long Term Incentive Plan [Member] USD ($)	Dec. 31, 2011 Class A [Member] Long Term Incentive Plan [Member] USD ($)	Dec. 31, 2010 Class A [Member] Long Term Incentive Plan [Member] USD ($)	Dec. 31, 2009 Class A [Member] Long Term Incentive Plan [Member] USD ($)	Dec. 31, 2012 Class A [Member] UAW [Member] USD ($)	Dec. 31, 2011 Class A [Member] UAW [Member] USD ($)	Dec. 31, 2011 Class B Long Term Incentive Plan [Member] USD ($)	Dec. 31, 2010 Class B Long Term Incentive Plan [Member] USD ($)	Dec. 31, 2009 Class B Long Term Incentive Plan [Member] USD ($)	Dec. 31, 2012 Selling General And Administrative Expense [Member] USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company recognized total stock compensation expense, net of forfeitures		$ 15.3		$ 11.2	$ 28.8
Number of shares granted							104,405	104	185			29,271	29	30	33						35,578	21,590	618,804	6,153	548,334	1,826	852,294					92,250	500
Grant Date Of Fair Value Of Shares Granted	0.7						2.5														1.1	1.1	15.3	0.1	12.9	0.1	11.0					2.2	0.1
Accelerated Vesting Expense		0.9
Restricted Stock Award, Forfeitures								0.2	0.1					0.1				0.5	0.2									2.5	3.3	2.7
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value								4.3	0.3	3.2			0.6	0.7	0.7			5.1	5.3									10.0	5.3	21.1				0.8
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights		1,500,000	1,500,000	2,300,000	2,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period																												774	550	1,568
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized						18.1		0.3					0.2
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition		0.3	2.5														2.5
Number of years from grant date to vest																	9 years
Stock Granted During Period, Value, Share-based Compensation, Gross								2.5	4.7				0.7	0.7	0.7													18.8	13.0	32.6
Allocated Share-based Compensation Expense		15.3		11.2	28.8			2.9	3.9	0.4			0.7	0.7	0.7				1.8									11.9	7.0	25.5					0.4		15.3
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized													3,000,000				12,000,000
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense		5.6		4.1	10.8
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Intrinsic Value						$ 28.9		$ 1.6					$ 0.5				$ 14.9
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period																	4 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		2,700,000	2,700,000	2,600,000	2,900,000			96	171		278		29	27	33	56	880	880	1,366	1,840								1,704	1,558	1,490	1,097				28	28
Allocated Share Based Compensation Expense Max Value																		0.1																0.1
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited								9	4					3				40	8									115	175	145
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period								170	10	278			27	33	56			446	466									513	307	1,030				28
Share Based Compensation Arrangement Grant Date Weighted Average Fair Value								$ 2.3	$ 4.3		$ 3.2		$ 0.7	$ 0.6	$ 0.7	$ 0.7	$ 9.8	$ 9.8	$ 15.4	$ 20.9								$ 38.3	$ 32.0	$ 27.6	$ 18.8				$ 0.8	$ 0.8
EIP Shares Sold To OffSe tParticpants Personal Income Tax Expense																	753