Consolidated Statements of Cash Flows (Parenthetical) $ in Millions			6 Months Ended
		Jun. 23, 2016 USD ($) item	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)
Supplemental Schedule of Noncash Investing and Financing Activities
Cash dividends declared, but not yet paid			$ 4.2	$ 4.2
Previous percentage ownership of noncontrolling owners			49.00%
Assets acquired, net of cash	[1]		$ 31.3
Liabilities assumed	[1]		$ 1.7
Tobras
Supplemental Schedule of Noncash Investing and Financing Activities
Previous percentage ownership of noncontrolling owners		49.00%
Tobras | Disposal Group, Held-for-sale, Not Discontinued Operations
Supplemental Schedule of Noncash Investing and Financing Activities
Previous percentage ownership of noncontrolling owners		49.00%
Settlement of promissory notes		$ 17.7
Number of promissory notes settled in acquisition | item		2

[1] Amounts may not add due to rounding