Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 29, 2018	Jun. 29, 2018
United Kingdom
Disaggregation of Revenue [Line Items]
Proceeds from sale of surplus land	$ 6.4	$ 6.4

The cash inflow from the sale of land held for investment; excludes sales of land held as inventory or productive use.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585

Name:	us-gaap_ProceedsFromSaleOfLandHeldforinvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration