Debt (Details) (USD $)	1 Months Ended			1 Months Ended	9 Months Ended		9 Months Ended
	Jul. 31, 2012 Term Loan Facility	Sep. 27, 2014 Term Loan Facility	Sep. 27, 2012 Term Loan Facility	Jul. 31, 2012 Agreement	Sep. 27, 2014 Agreement	Jul. 31, 2012 Revolving Credit Facility	Sep. 27, 2014 Term loan facility and revolving credit facility, other than swingline loans LIBOR Low end of range	Sep. 27, 2014 Term loan facility and revolving credit facility, other than swingline loans LIBOR High end of range	Sep. 27, 2014 Term loan facility and revolving credit facility, other than swingline loans Federal Funds	Sep. 27, 2014 Term loan facility and revolving credit facility, other than swingline loans one-month LIBOR	Sep. 27, 2014 Term loan facility, revolving credit facility, swingline and other loans Base rate Low end of range	Sep. 27, 2014 Term loan facility, revolving credit facility, swingline and other loans Base rate High end of range
Debt
Maximum borrowing capacity	$ 100,000,000			$ 230,000,000		$ 130,000,000
Term of debt instrument				5 years
Percentage of principal amortization in each of the first two years	5.00%
Number of years for which the percentage of principal amortization is five percent	2 years
Percentage of principal amortization in each of the next three years	10.00%
Number of years for which the percentage of principal amortization is ten percent	3 years
Sublimit on letters of credit						25,000,000
Sublimit on swingline loan						10,000,000
Additional increase in borrowing capacity of the line of credit available at the entity's option						50,000,000
Amount borrowed under the term loan facility			100,000,000
Interest rate added to the base rate (as a percent)							1.50%	2.50%	0.50%	1.00%	0.50%	1.50%
Maximum leverage ratio					2.5
Minimum fixed charge coverage ratio					1.50
Fixed interest rate percentage		0.764%
Combined interest rate percentage		2.514%
Term Loan Facility
2014		3,750,000
2015		10,000,000
2016		10,000,000
2017		67,500,000
Total debt		$ 91,250,000