Summary of Significant Accounting Policies - Marketable Securities (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Percentage of ownership in Swiss franchise	49.00%
Swiss franchise investment portfolio market value	$ 207.0	$ 202.3
Swiss franchise realized gains	2.9	2.3	$ 2.5
Swiss franchise realized losses	1.0	1.1	0.5
Other-than-temporary impairment gains	$ (0.3)	$ (0.2)
Other-than-temporary impairment loss			$ 0.1

Other than Temporary Impairment Gains, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities

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- Definition

Investment in debt and equity securities that are categorized as neither held-to-maturity or trading, associated with a Swiss franchise in which we hold a 49 percent interest.

+ References

No definition available.

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563

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This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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- Definition

The amount of other than temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments (OTTI) on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

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