Long-Term Debt Obligations (Details) (USD $)	3 Months Ended		3 Months Ended					3 Months Ended			3 Months Ended					3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Revolving credit facility item	Jun. 25, 2013 Revolving credit facility	Jun. 24, 2013 Revolving credit facility	Mar. 31, 2014 Revolving credit facility EAS	Mar. 31, 2014 Revolving credit facility Actual	Mar. 31, 2014 Revolving credit facility Minimum	Mar. 31, 2014 Revolving credit facility Minimum Covenant Requirement	Mar. 31, 2014 Revolving credit facility Minimum Actual	Mar. 31, 2014 Revolving credit facility Maximum	Mar. 31, 2014 Revolving credit facility Maximum Through December 31, 2014	Mar. 31, 2014 Revolving credit facility Maximum Through December 31, 2015	Mar. 31, 2014 Revolving credit facility Maximum Through maturity	Mar. 31, 2014 Revolving credit facility Maximum Covenant Requirement	Mar. 31, 2014 Revolving credit facility Maximum Actual	Mar. 31, 2014 Revolving credit facility Base rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 0.75	Mar. 31, 2014 Revolving credit facility Base rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 0.75 to 1.50	Mar. 31, 2014 Revolving credit facility Base rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.50 to 2.25	Mar. 31, 2014 Revolving credit facility Base rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.25 or greater	Mar. 31, 2014 Revolving credit facility Eurodollar rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 0.75	Mar. 31, 2014 Revolving credit facility Eurodollar rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 0.75 to 1.50	Mar. 31, 2014 Revolving credit facility Eurodollar rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.50 to 2.25	Mar. 31, 2014 Revolving credit facility Eurodollar rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.25 or greater	Mar. 31, 2014 Notes to former owners	Dec. 31, 2013 Notes to former owners
Long-Term Debt Obligations
Total debt	$ 9,000,000	$ 2,000,000	$ 7,000,000																						$ 2,000,000	$ 2,000,000
Less - current portion	(2,000,000)	(2,000,000)
Total long-term portion of debt	7,000,000
Borrowing capacity				175,000,000	125,000,000	2,500,000
Outstanding borrowings			7,000,000			0
Letters of credit amount outstanding			50,600,000
Credit available			117,400,000			2,500,000
Number of interest rate options			2
Additional per annum interest margin added under:
Variable rate basis																	Base rate	Base rate	Base rate	Base rate	Eurodollar rate	Eurodollar rate	Eurodollar rate	Eurodollar rate
Additional per annum interest margin (as a percent)																	0.25%	0.50%	0.75%	1.00%	1.25%	1.50%	1.75%	2.00%
Weighted average interest rate (as a percent)			3.50%			2.70%																			3.30%
Payments of debt	0
Letter of credit fees (as a percent)								1.25%			2.00%
Commitment fees payable on unused portion of the facility (as a percent)								0.20%			0.35%
Principal financial covenants
Leverage ratio			0.14									3.00	2.75	2.50
Net leverage ratio used to determine exclusion of stock repurchases and the payment of dividends for calculation of the fixed charge coverage ratio															1.50
Amount of stock repurchases to maintain maximum net leverage ratio																25,000,000
Net leverage ratio after giving effect to stock repurchases for calculation of the fixed charge coverage ratio																1.50
Number of quarters of capital expenditures, tax provision, dividends and stock repurchase payments used for calculation of fixed charge coverage ratio			4
Fixed charge coverage ratio							10.19			2.00
Permitted amount of acquisitions per transaction											20,000,000
Aggregate purchase price of current acquisition and acquisitions in the preceding 12 month period for determining permitted amount of acquisition per transaction											$ 50,000,000
Net leverage ratio used as basis for other restrictions									2.00