Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities
Net income	$ 17,807	$ 16,247
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization of property and equipment	7,127	7,030
Amortization of other intangible assets	615	285
Loss on asset disposals and impairments of property and equipment	391	725
Deferred income taxes	(2,155)	(806)
Equity in net loss of affiliate	2,356	2,532
Distributions from affiliate	2,949	2,650
Bad debt expense	430	505
Non-cash share-based compensation	2,168	2,005
Changes in operating assets and liabilities
Trade accounts receivable	11,054	10,615
Prepaid expenses and other assets	742	4,234
Accounts payable	(815)	715
Accrued expenses and other current liabilities	(4,703)	(7,998)
Deferred revenue	1,057	(2,090)
Other noncurrent liabilities	1,148	1,354
Net cash provided by operating activities	40,171	38,003
Cash flows from investing activities
Additions to property and equipment	(4,936)	(7,204)
Net cash used in investing activities	(4,936)	(7,204)
Cash flows from financing activities
Proceeds from stock option exercises and stock purchase plan	1,120	1,261
Stock repurchases	(17,330)
Dividends paid to stockholders	(2,727)	(2,697)
Tax benefits realized from share-based awards	132	267
Debt borrowings		5,000
Debt repayments		(30,000)
Net cash used in financing activities	(18,805)	(26,169)
Effect of exchange rate changes on cash and cash equivalents	40	2
Net change in cash and cash equivalents	16,470	4,632
Cash and cash equivalents at beginning of period	19,715	18,925
Cash and cash equivalents at end of period	$ 36,185	$ 23,557