Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

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Debt - Total interest expense recognized on the Convertible Notes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Unamortized discount					$ 8.5
2018 secured railcar equipment notes
Debt Instrument [Line Items]
Unamortized discount	$ 0.2		$ 0.2
3 7/8% Convertible Subordinated Notes Due 2036 \| Convertible subordinated notes
Debt Instrument [Line Items]
Coupon rate interest	0.0	$ 4.4	7.2	$ 13.1
Amortized debt discount	0.0	4.7	8.2	13.8
Total interest expense recognized on the Convertible Subordinated Notes	0.0	$ 9.1	15.4	$ 26.9
Trinity Rail Leasing 2018 \| 2018 secured railcar equipment notes \| Secured debt
Debt Instrument [Line Items]
Unamortized discount	$ 0.2		$ 0.2		$ 0.0