Debt (Details Textual) (USD $)	0 Months Ended	3 Months Ended
	Jan. 10, 2012	Jul. 01, 2012	Dec. 31, 2011
Debt (Additional Textual) [Abstract]
Increase in revolving credit facility	$ 200,000,000
Revolving credit facility expand	300,000,000
Reduced the applicable margin by basis points Percentage	0.25%
Revolving credit agreement, weighted-average interest rate		1.80%	1.90%
Revolving credit agreement current		100,400,000	72,800,000
Revolving credit agreement		97,000,000	74,400,000
Maximum revolving credit agreement		200,000,000	150,000,000
Percentage of commitment fee		0.35%
Amount of swap agreement		50,000,000
Accrued liability		79,000
Non-current liability		753,000
Unrealized loss on cash flow hedges		832,000
Letter of credit [Member]
Debt (Textual) [Abstract]
Standby letters of credit		$ 2,600,000	$ 2,800,000