CONSOLIDATED STATEMENT OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating activities:
Net income	$ 17,396	$ 20,023
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	30,162	26,871
Stock-based compensation expense	6,122	7,095
Excess tax benefit from exercised stock options	(4,244)	(6,842)
Deferred income taxes	(2,531)	(3,236)
Increase in allowance for doubtful debts	4,140	1,669
Change in fair value of contingent consideration	20
Loss on disposal of fixed assets	184	59
Changes in operating assets and liabilities:
Accounts receivable	(14,912)	(8,020)
Prepaid expenses	1,878	(6,195)
Prepaid income taxes	(2,742)	6,068
Other current assets	(73)	593
Other assets	7	(101)
Accounts payable, accrued expenses and other liabilities	(3,090)	(7,868)
Estimated liability for appeals	3,554	6,505
Net cash provided by operating activities	35,871	36,621
Investing activities:
Purchases of property and equipment	(12,734)	(15,789)
Investment in common stock	(500)	(3,024)
Acquisitions, net		(1,605)
Investment in capitalized software	(1,996)	(1,006)
Net cash used in investing activities	(15,230)	(21,424)
Financing activities:
Financing related to revolving debt	(7,619)	(8,750)
Repayment of revolving debt	(25,000)
Purchases of treasury stock		(10,617)
Payments on contingent consideration		(250)
Payments on capital lease obligations	(838)	(387)
Proceeds from exercise of stock options	6,309	7,453
Payments of tax withholdings on behalf of employees for net-share settlement for stock-based compensation	(1,498)	(1,127)
Excess tax benefit from exercised stock options	4,244	6,842
Net cash used in financing activities	(24,402)	(6,836)
Net (decrease)/increase in cash and cash equivalents	(3,761)	8,361
Cash and cash equivalents at beginning of period	135,227	97,003
Cash and cash equivalents at end of period	131,466	105,364
Supplemental disclosure of cash flow information:
Cash paid for income taxes	19,881	10,312
Cash paid for interest	4,308	6,933
Supplemental disclosure of noncash investing activities:
Accrued property and equipment purchases	1,655	1,187
Equipment purchased through capital leases	$ 2,196	$ 1,629