Minimum period the individual is required to perform services to be fully vested under the deferred compensation arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
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401(k) Profit Sharing, Deferred Compensation and Long-term Incentive Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plan Disclosure [Line Items]
Contributions	$ 5.7	$ 5.8	$ 5.4
Other Noncurrent Liabilities
Defined Contribution Plan Disclosure [Line Items]
Balance due to participants	$ 32.9	$ 27.9
Minimum
Defined Contribution Plan Disclosure [Line Items]
Discretionary contributions vesting period	1 year
Maximum
Defined Contribution Plan Disclosure [Line Items]
Discretionary contributions vesting period	7 years