Significant Accounting Policies - Deferred Income Tax Accounts and Tax Reserves (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2017	Apr. 01, 2018
Significant Accounting Policies
Provisional one-time Tax Act tax benefit from remeasurement of deferred tax assets, liabilities and related valuation allowances	$ 7.0
Net deferred income tax liability		$ 5.5

Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences without jurisdictional netting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e31931-109318

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

Name:	us-gaap_DeferredTaxLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant