Commitments, Contingencies and Litigation Settlement (Details) - USD ($) $ in Millions	1 Months Ended				3 Months Ended			9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2013	May 31, 2013	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 28, 2017
Loss Contingencies [Line Items]
Litigation settlement gain					$ 0.0	$ 3.3	$ 0.0	$ 3.3	$ 0.0
TMK IPSCO
Loss Contingencies [Line Items]
Direct damages sought				$ 10.0
Damages awarded		$ 2.2	$ 5.2
Loss contingency accrual										$ 7.3
TMK IPSCO | Settled Litigation
Loss Contingencies [Line Items]
Payments for legal settlements	$ 4.0