Fair Value Measurements (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	0 Months Ended		3 Months Ended		3 Months Ended	12 Months Ended
	Aug. 24, 2012 Senior Redeemable Preferred Stock [Member]	May 16, 2012 Senior Redeemable Preferred Stock [Member]	Mar. 31, 2013 Senior Redeemable Preferred Stock [Member]	Dec. 31, 2012 Senior Redeemable Preferred Stock [Member]	Mar. 31, 2013 Public Preferred Stock [Member]	Dec. 31, 2012 Public Preferred Stock [Member]	Dec. 31, 1991 Public Preferred Stock [Member]	Dec. 31, 1990 Public Preferred Stock [Member]	Mar. 31, 2012 I T Logistics Inc [Member] Subordinated Promissory Note [Member]	Jul. 01, 2011 I T Logistics Inc [Member] Subordinated Promissory Note [Member]	Mar. 31, 2012 I T Logistics Inc [Member] Liability Due in Installments [Member]	Jul. 01, 2011 I T Logistics Inc [Member] Liability Due in Installments [Member]	Mar. 31, 2013 Carrying (Reported) Amount, Fair Value Disclosure [Member] Public Preferred Stock [Member]	Dec. 31, 2012 Carrying (Reported) Amount, Fair Value Disclosure [Member] Public Preferred Stock [Member]	Mar. 31, 2013 Estimate of Fair Value, Fair Value Disclosure [Member] Public Preferred Stock [Member]	Dec. 31, 2012 Estimate of Fair Value, Fair Value Disclosure [Member] Public Preferred Stock [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Face value of debt instrument									$ 15	$ 15	$ 7
Fair value of debt instrument									11.7			6.9
Carrying amount of debt instrument									12.2		1.4
Percentage of stock redeemed (in hundredths)	36.00%	26.70%
Redemption price of senior preferred stock	2.0	2.0
Carrying amount of senior redeemable preferred stock			4.0	4.0
Preferred stock dividend rate per annum (in hundredths)			14.125%		12.00%	12.00%	6.00%	6.00%
Public preferred stock par value (in dollar per share)					$ 0.01
Public preferred stock													$ 113.4	$ 112.5	$ 46.8	$ 47.8