Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Receivables, net of allowance for doubtful accounts	$ 8.3	$ 5.5
Property, plant and equipment of TRIP Holdings	5,407.9	5,202.2
Accumulated depreciation on property, plant and equipment of TRIP Holdings	1,228.4	1,090.2
Restricted cash of TRIP Holdings	240.3	207.1
Debt unamortized discount	99.8	111.1
Preferred stock, shares authorized	1.5	1.5
Preferred stock, shares unissued	1.5	1.5
Common stock, shares authorized	200.0	200.0
Common Stock, Shares, Issued	81.7	81.7
Common Stock, Shares, Outstanding	81.7	81.7
Treasury stock, Shares	1.5	1.9
TRIP Holdings [Member]
Property, plant and equipment of TRIP Holdings	1,257.7	1,282.1
Accumulated depreciation on property, plant and equipment of TRIP Holdings	122.7	90.3
Restricted cash of TRIP Holdings	74.6	46.0
Debt unamortized discount	$ 99.8	$ 111.1