Derivative Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2017		Dec. 31, 2016	Dec. 31, 2006
Derivative [Line Items]
Total stockholders' equity	$ 4,348.9	[1]	$ 4,311.1
AOCL – loss/ (income)
Derivative [Line Items]
Total stockholders' equity	0.1		$ (0.1)
Designated as hedging instrument | Interest rate swap, Expired, 2006 secured railcar equipment notes
Derivative [Line Items]
Notional Amount	$ 200.0			$ 200.0
Interest Rate	4.87%
Liability	$ 0.0
Designated as hedging instrument | Interest rate swap, Expired, 2006 secured railcar equipment notes | AOCL – loss/ (income)
Derivative [Line Items]
Total stockholders' equity	(0.6)
Designated as hedging instrument | Interest rate swap, Expired, 2006 secured railcar equipment notes | Noncontrolling Interest
Derivative [Line Items]
Total stockholders' equity	0.0
Designated as hedging instrument | Interest rate swap, Expired, TRIP Holdings warehouse loan
Derivative [Line Items]
Notional Amount	$ 788.5
Interest Rate	3.60%
Liability	$ 0.0
Designated as hedging instrument | Interest rate swap, Expired, TRIP Holdings warehouse loan | AOCL – loss/ (income)
Derivative [Line Items]
Total stockholders' equity	5.4
Designated as hedging instrument | Interest rate swap, Expired, TRIP Holdings warehouse loan | Noncontrolling Interest
Derivative [Line Items]
Total stockholders' equity	7.3
Designated as hedging instrument | Interest rate swap, Open, TRIP Master Funding secured railcar equipment notes
Derivative [Line Items]
Notional Amount	$ 37.0
Interest Rate	2.62%
Liability	$ 0.7
Designated as hedging instrument | Interest rate swap, Open, TRIP Master Funding secured railcar equipment notes | AOCL – loss/ (income)
Derivative [Line Items]
Total stockholders' equity	0.3
Designated as hedging instrument | Interest rate swap, Open, TRIP Master Funding secured railcar equipment notes | Noncontrolling Interest
Derivative [Line Items]
Total stockholders' equity	$ 0.4

[1] (unaudited)