Long-Term Debt Obligations (Details 3) (USD $)	3 Months Ended								12 Months Ended								12 Months Ended											12 Months Ended							12 Months Ended								0 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Revolving credit facility item	Jun. 25, 2013 Revolving credit facility	Jun. 24, 2013 Revolving credit facility	Dec. 31, 2013 Revolving credit facility EAS	Dec. 31, 2013 Revolving credit facility Actual	Dec. 31, 2013 Revolving credit facility Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 0.75	Dec. 31, 2013 Revolving credit facility Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 0.75 to 1.50	Dec. 31, 2013 Revolving credit facility Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.50 to 2.25	Dec. 31, 2013 Revolving credit facility Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.25 or greater	Dec. 31, 2013 Revolving credit facility Minimum Covenant Requirement	Dec. 31, 2013 Revolving credit facility Minimum Actual	Dec. 31, 2013 Revolving credit facility Maximum	Dec. 31, 2013 Revolving credit facility Maximum Through December 31, 2014	Dec. 31, 2013 Revolving credit facility Maximum Through December 31, 2015	Dec. 31, 2013 Revolving credit facility Maximum Through maturity	Dec. 31, 2013 Revolving credit facility Maximum Covenant Requirement	Dec. 31, 2013 Revolving credit facility Maximum Actual	Dec. 31, 2013 Revolving credit facility Base rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 0.75	Dec. 31, 2013 Revolving credit facility Base rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 0.75 to 1.50	Dec. 31, 2013 Revolving credit facility Base rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.50 to 2.25	Dec. 31, 2013 Revolving credit facility Base rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.25 or greater	Dec. 31, 2013 Revolving credit facility Base rate Federal Funds Rate	Dec. 31, 2013 Revolving credit facility Base rate Wells Fargo Bank, N.A. Prime Rate	Dec. 31, 2013 Revolving credit facility Base rate One-month LIBOR	Dec. 31, 2013 Revolving credit facility Base rate Six-month LIBOR	Dec. 31, 2013 Revolving credit facility Eurodollar rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 0.75	Dec. 31, 2013 Revolving credit facility Eurodollar rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 0.75 to 1.50	Dec. 31, 2013 Revolving credit facility Eurodollar rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.50 to 2.25	Dec. 31, 2013 Revolving credit facility Eurodollar rate Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.25 or greater	Dec. 31, 2013 Revolving credit facility Eurodollar rate One-month LIBOR	Dec. 31, 2013 Revolving credit facility Eurodollar rate Six-month LIBOR	Jul. 31, 2013 Other debt	Dec. 31, 2013 Other debt	Dec. 31, 2013 Notes to former owners
Long-Term Debt Obligations
Borrowing capacity													$ 175,000,000	$ 125,000,000	$ 2,500,000
Financing and professional cost													600,000
Unamortized costs													700,000
Outstanding borrowings												0
Letters of credit amount outstanding												48,100,000
Credit available												126,900,000			2,500,000
Book value of assets pledged as collateral												69,500,000
Number of quarters of net earnings used for the calculation of the credit facility adjusted EBITDA												4
Reconciliation of Credit Facility Adjusted EBITDA to net income
Net income (loss) including noncontrolling interests	5,935,000	11,612,000	8,314,000	2,695,000	5,145,000	5,325,000	4,047,000	(2,668,000)	28,556,000	11,849,000	(36,492,000)	28,556,000
Income taxes-continuing operations									18,148,000	10,045,000	(5,463,000)	18,148,000
Interest expense, net												1,328,000
Depreciation and amortization expense												18,572,000
Stock compensation expense									4,000,000	2,800,000	3,600,000	3,974,000
Income taxes - discontinued operation												(119,000)
EBITDA attributable to noncontrolling interests												(2,342,000)
Credit Facility Adjusted EBITDA												68,117,000
Principal financial covenants
Leverage ratio												0.03												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																10.88						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
Number of interest rate options												2
Period of Credit Facility Adjusted EBITDA for determining additional margins												12 months
Market rates relating to interest options
Variable rate basis																													Base rate	Base rate	Base rate	Base rate			One-month LIBOR	Six-month LIBOR	Eurodollar rate	Eurodollar rate	Eurodollar rate	Eurodollar rate
Interest rate margin (as a percent)																													0.25%	0.50%	0.75%	1.00%	0.50%		1.00%		1.25%	1.50%	1.75%	2.00%
Market rate (as a percent)																																	0.59%	3.25%	1.20%						0.20%	0.35%
Additional per annum interest margin added under:
Variable rate basis																													Base rate	Base rate	Base rate	Base rate			One-month LIBOR	Six-month LIBOR	Eurodollar rate	Eurodollar rate	Eurodollar rate	Eurodollar rate
Additional per annum interest margin (as a percent)																													0.25%	0.50%	0.75%	1.00%	0.50%		1.00%		1.25%	1.50%	1.75%	2.00%
Letter of credit fees (as a percent)																	1.25%	1.50%	1.75%	2.00%
Commitment fees payable on unused portion of the facility (as a percent)																	0.20%	0.25%	0.30%	0.35%
Estimated interest rate (as a percent)												1.60%
Payments of debt									$ 5,400,000	$ 7,349,000	$ 14,387,000																																$ 2,400,000
Other disclosures
Weighted average interest rate (as a percent)															2.70%																													0.21%	3.30%