Fair Value (Tables)

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Assets and liabilities measured at fair value on a recurring basis

The following tables present the fair value hierarchy for those financial assets and liabilities measured at fair value on a recurring basis as of June 30, 2017 and December 31, 2016:

	June 30, 2017
	Total		Level 1		Level 2		Level 3
Assets:
Cash and cash equivalents	$	429.0	$	425.3	$	3.7	$	—
Cash and cash equivalents measured at net asset value	16.1		—		—		—
Restricted cash	2.8		2.8		—		—
Short-term investments	14.5		—		14.5		—
Short-term investments measured at net asset value	4.8		—		—		—
Foreign currency hedges	1.2		—		1.2		—
Total Assets	$	468.4	$	428.1	$	19.4	$	—
Liabilities:
Foreign currency hedges	$	5.7	$	—	$	5.7	$	—
Total Liabilities	$	5.7	$	—	$	5.7	$	—

	December 31, 2016
	Total		Level 1		Level 2		Level 3
Assets:
Cash and cash equivalents	$	129.6	$	125.0	$	4.6	$	—
Cash and cash equivalents measured net asset value	19.2		—		—		—
Restricted cash	2.7		2.7		—		—
Short-term investments	9.4		—		9.4		—
Short-term investments measured at net asset value	2.3		—		—		—
Foreign currency hedges	9.9		—		9.9		—
Total Assets	$	173.1	$	127.7	$	23.9	$	—
Liabilities:
Foreign currency hedges	$	2.1	$	—	$	2.1	$	—
Total Liabilities	$	2.1	$	—	$	2.1	$	—

Fair Value Measurements, Nonrecurring [Table Text Block]

The following table presents those assets measured at fair value on a nonrecurring basis for the six months ended June 30, 2016 using Level 3 inputs:

	Carrying Value		Fair Value Adjustment			Fair Value
Long-lived assets held for sale:
Land	$	0.2	$	(0.2	)	$	—
Total long-lived assets held for sale	$	0.2	$	(0.2	)	$	—
Long-lived assets held and used:
Altavista bearing plant	$	5.7	$	(2.4	)	$	3.3
Total long-lived assets held and used	$	5.7	$	(2.4	)	$	3.3