Fair Value Measurements (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	0 Months Ended			9 Months Ended		9 Months Ended	12 Months Ended
	Aug. 24, 2012 Senior Redeemable Preferred Stock [Member]	May 16, 2012 Senior Redeemable Preferred Stock [Member]	Apr. 08, 2011 Senior Redeemable Preferred Stock [Member]	Sep. 30, 2012 Senior Redeemable Preferred Stock [Member]	Dec. 31, 2011 Senior Redeemable Preferred Stock [Member]	Sep. 30, 2012 Public Preferred Stock [Member]	Dec. 31, 2011 Public Preferred Stock [Member]	Dec. 31, 1991 Public Preferred Stock [Member]	Dec. 31, 1990 Public Preferred Stock [Member]	Nov. 01, 2012 IT Logistics, Inc [Member] Subordinated Promissory Note [Member]	Sep. 30, 2012 IT Logistics, Inc [Member] Subordinated Promissory Note [Member]	Dec. 31, 2011 IT Logistics, Inc [Member] Subordinated Promissory Note [Member]	Jun. 30, 2011 IT Logistics, Inc [Member] Subordinated Promissory Note [Member]	Sep. 30, 2012 Carrying (Reported) Amount, Fair Value Disclosure [Member] Public Preferred Stock [Member]	Dec. 31, 2011 Carrying (Reported) Amount, Fair Value Disclosure [Member] Public Preferred Stock [Member]	Sep. 30, 2012 Estimate of Fair Value, Fair Value Disclosure [Member] Public Preferred Stock [Member]	Dec. 31, 2011 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	$ 15	$ 15
Carrying amount of debt instrument											12.5	12.1
Redemption price of senior preferred stock	2.0	2.0	2.1
Fair value of debt instrument													11.7
Percentage of stock redeemed (in hundredths)	36.00%	26.70%	22.30%
Carrying amount of senior redeemable preferred stock				4.0	8.2
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														$ 111.5	$ 108.6	$ 42.2	$ 65.3