Investment in TRIP Holdings (Details Textual) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Investment in TRIP Holdings (Textual) [Abstract]
Railcars purchased from the Company by subsidiaries of TRIP Holdings		$ 1,331.4		$ 1,331.4
Ownership percentage in TRIP Holdings		57.00%		57.00%
Number of other third-party equity investors in TRIP Holdings		3		3
TRIP Holdings
Investment in TRIP Holdings (Textual) [Abstract]
New debt issued to repay outstanding borrowings of TRIP Warehouse Loan	1,032.0
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		90.00%		90.00%
Percentage of the equity investor's net investment specified as amount payable to equity investor under certain limited circumstances		100.00%		100.00%
Remaining equity commitment outstanding		0		0
Administrative fees to TILC by TRIP Holdings and subsidiaries		$ 1.2	$ 1.2	$ 3.7	$ 3.1