Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating activities
Net Income	$ 147,335	$ 107,896	$ 89,052
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	11,451	11,261	9,648
Stock-based compensation	21,743	26,755	2,666
Provision for losses on accounts receivable	19,226	18,883	32,593
Amortization of deferred financing costs	1,864	2,016	1,842
Amortization of intangible assets	19,590	17,205	13,900
Amortization of premium on receivables	3,266	3,263	3,257
Deferred income taxes	(2,920)	(3,952)	4,395
Loss on early extinguishment of debt	2,669
Changes in operating assets and liabilities (net of acquisitions):
Restricted cash	6,579	5,639	3,243
Accounts receivable	(80,024)	(38,960)	2,345
Prepaid expenses and other current assets	17,581	(3,506)	11,002
Other assets	(1,935)	63	(370)
Excess tax benefits related to stock-based compensation	(13,727)	(10,710)
Accounts payable, accrued expenses, and customer deposits	126,927	3,902	5,217
Net cash provided by operating activities	279,625	139,755	178,790
Investing activities
Acquisitions, net of cash acquired	(333,763)	(10,022)	(231,097)
Purchases of property and equipment	(13,454)	(11,194)	(9,677)
Net cash used in investing activities	(347,217)	(21,216)	(240,774)
Financing activities
Net proceeds from initial public offering		9,560
Excess tax benefits related to stock-based compensation	13,727	10,710
Proceeds from (payments on) securitization facility, net	136,000	(74,000)
Deferred financing costs paid	(7,839)	(1,067)
Proceeds from notes payable	425,000
Payment of dividends on convertible preferred stock		(7,634)
Proceeds from issuance of common stock	8,477	538	266
Proceeds from issuance of convertible preferred stock, net			93,696
Principal payments on notes payable	(338,965)	(24,634)	(21,658)
Principal payments on other obligations		(17)	(66)
Other	(179)
Net cash provided by (used in) financing activities	236,221	(86,544)	72,238
Effect of foreign currency exchange rates on cash	1,726	(1,892)	4,092
Net increase in cash	170,355	30,103	14,346
Cash and cash equivalents at beginning of year	114,804	84,701	70,355
Cash and cash equivalents at end of year	285,159	114,804	84,701
Supplemental cash flow information
Cash paid for interest	14,961	21,409	22,242
Cash paid for income taxes	49,205	45,998	28,094
Adoption of new accounting guidance related to asset securitization facility		218,000
Non-cash investing activity
Non-cash issuance of preferred stock			$ 8,000