Goodwill (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($)
Change in the carrying amount of goodwill
Balance at the beginning of the period	$ 1,724.8
Acquisition	96.0
Effect of foreign currency translation	3.8
Balance at the end of the period	1,824.6
Accumulated impairment losses	0.0
Tubular Steel
Change in the carrying amount of goodwill
Balance at the end of the period	96.0
Goodwill, tax deductible amount	$ 96.0