Partially-Owned Leasing Subsidiaries (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) board_member subsidiary
Partially-owned subsidiaries
Noncontrolling Interest [Line Items]
Trinity guarantees of subsidiary-related activities	$ 0
Railcar Leasing and Management Services Group | 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 subsidiaries	$ 224,400,000
Weighted average ownership interest	39.00%
Weighted average interest owned by institutional investors	61.00%
Railcar Leasing and Management Services Group | TRIP Holdings
Noncontrolling Interest [Line Items]
Remaining equity commitment outstanding from TILC	$ 5,700,000
Remaining equity commitment outstanding from third parties	$ 12,900,000