Partially-Owned Leasing Subsidiaries (Details Textual) - Leasing Group $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($) board_member subsidiary
Partially-owned subsidiaries
Noncontrolling Interest [Line Items]
Number of subsidiaries | subsidiary	2
Number of board members | board_member	7
Number of TILC designated board members | board_member	2
Carrying value of investment in partially-owned subsidiary	$ 227.0
Weighted average ownership interest in partially-owned subsidiary	39.00%
Weighted average ownership interest by institutional investors	61.00%
TRIP Holdings
Noncontrolling Interest [Line Items]
Remaining equity commitment outstanding (up to)	$ 5.7
Remaining equity commitment outstanding from third parties (up to)	$ 12.9