Debt - Debt Acquired in Acquisition (Details)		6 Months Ended
	Sep. 16, 2008 USD ($) subsidiary	Jul. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Debt instrument, face amount		$ 300,300,000	$ 300,800,000
Carrying Amount		294,100,000	$ 294,300,000
10-year term loan
Debt Instrument [Line Items]
Debt instrument, face amount	$ 10,000,000.0
Maturity period	10 years
Number of subsidiaries acquired | subsidiary	1
Carrying Amount		300,000
Quarterly installment payment - principal		$ 300,000
10-year term loan | LIBOR rate
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%