Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016	[1]
Statement of Comprehensive Income [Abstract]
Net earnings	$ 71.6	$ 120.8	$ 53.8
Other comprehensive income, net of tax:
Foreign currency translation adjustments, net of tax expense of $0.2 million, tax expense of $0.0 million and tax benefit of $0.4 million, respectively	16.4	(0.6)	(19.4)
Less: Reclassification adjustments included in net earnings	0.0	(0.1)	(0.2)
Foreign currency translation adjustments	16.4	(0.7)	(19.6)
Unrealized gains (losses) on investment, net of tax expense of $30.2 million, tax benefit of $0.7 million and tax expense of $15.8 million, respectively	56.2	(1.1)	28.6
Pension liability adjustments, net of tax expense of $0.1 million, $0.0 million and $0.0 million, respectively	(0.6)	(0.3)	0.5
Less: Reclassification adjustments included in net earnings	0.1	0.1	0.1
Pension liability adjustments	(0.5)	(0.2)	0.6
Other comprehensive income (loss)	72.1	(2.0)	9.6
Comprehensive Income	$ 143.7	$ 118.8	$ 63.4

[1] Fiscal year included 53 weeks.