Revolving Credit Facility (Details) $ in Thousands	12 Months Ended
	Jan. 01, 2016 USD ($) multiple	Dec. 31, 2014
Revolving credit facility
Debt issuance fees	$ 1,161
Companies net worth	270,200
Revolving Credit Facility.
Revolving credit facility
Line of Credit Facility, Covenants Minimum Net Worth	177,500
Revolving credit limit	175,000
Potential future expansion of the Facility under accordion feature	$ 250,000
EBITDA multiplier | multiple	3.5
Borrowing capacity permitted to be used per formula	$ 43,400
Irrevocable letters of credit outstanding	11,300
Remaining borrowing capacity available for use	$ 32,100
Revolving Credit Facility. | Prime rate
Revolving credit facility
Weighted average interest rate (as a percent)	3.50%	2.70%
Revolving Credit Facility. | LIBOR | Minimum
Revolving credit facility
Interest rate margin per debt instrument (as a percent)	1.75%
Revolving Credit Facility. | LIBOR | Maximum
Revolving credit facility
Interest rate margin per debt instrument (as a percent)	3.00%