Investment in TRIP Holdings (Details Textual) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Investment in TRIP Holdings (Textual) [Abstract]
Ownership percentage in TRIP Holdings				57.00%
Investment in Subsidiary (Additional Textual) [Abstract]
Railcars purchased by TRIP from the Company		$ 1,325.2		$ 1,325.2
Number of other third-party equity investors in TRIP Holdings		3		3
TRIP Holdings [Member]
Investment in TRIP Holdings (Textual) [Abstract]
Remaining equity commitment outstanding		0		0
Additional borrowings debt instrument increase additional borrowings	1,032.0
Payments to TILC from TRIP Holdings and TRIP leasing		$ 1.2	$ 1.0	$ 2.5	$ 1.9
Percentage of the equity investor's net investment specified as amount payable to equity investor		90.00%		90.00%
Additional equity ownership to be acquired from the equity investor by the company if the option was exercised to its fullest extent		16.30%		16.30%
Percentage of the equity investor's net investment specified as amount payable to equity investor under certain limited circumstances		100.00%		100.00%