Consolidated Statements of Cash Flows (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Treasury shares obtained for tax payments on stock vesting	$ 672,000	$ 1,200,000	$ 940,000
Unrecognized tax position		3,400,000
Stock issued for acquisitions			1,550,000
2011 Acquisition
Percentage ownership interest transfer		26.32%
Addition paid in capital		206,000
Addition noncontrolling interest		294,000
Noncontrolling interest related to acquisitions		1,300,000
2008 Acquisition
Company Additional issued Shares			29,988
Stock issued for acquisitions			950,000
2010 Acquisition
Noncontrolling interest related to acquisitions			950,000
Company Additional issued Shares			20,162
Stock issued for acquisitions			$ 600,000