Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities
Net income	$ 284,501	$ 216,199	$ 147,335
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	16,885	14,116	11,451
Stock-based compensation	26,676	19,275	21,743
Provision for losses on accounts receivable	18,867	21,896	19,226
Amortization of deferred financing costs	3,276	2,279	1,864
Amortization of intangible assets	49,313	32,376	19,590
Amortization of premium on receivables	3,263	3,265	3,266
Deferred income taxes	(5,453)	(3,337)	(2,920)
Loss on early extinguishment of debt			2,669
Changes in operating assets and liabilities (net of acquisitions):
Restricted cash	5,430	2,088	6,579
Accounts receivable	(45,005)	(71,102)	(80,024)
Prepaid expenses and other current assets	(74)	(6,847)	17,581
Other assets	38,906	(46,553)	(1,935)
Excess tax benefits related to stock-based compensation	(32,535)	(29,355)	(13,727)
Accounts payable, accrued expenses, and customer deposits	11,635	(18,840)	126,927
Net cash provided by operating activities	375,685	135,460	279,625
Investing activities
Acquisitions, net of cash acquired	(728,343)	(190,447)	(333,763)
Purchases of property and equipment	(20,785)	(19,111)	(13,454)
Net cash used in investing activities	(749,128)	(209,558)	(347,217)
Financing activities
Excess tax benefits related to stock-based compensation	32,535	29,355	13,727
Repurchase of common stock		(200,000)
Proceeds from issuance of common stock	30,438	27,187	8,477
Borrowings on securitization facility, net	51,000	18,000	136,000
Deferred financing costs paid	(1,970)	(3,776)	(7,839)
Proceeds from notes payable		250,000	300,000
Principal payments on notes payable	(28,125)	(30,414)	(338,965)
Borrowings from revolver- A Facility	783,663	455,000	125,000
Payments on revolver- A Facility	(261,516)	(480,000)
Borrowings from revolver- B Facility	16,715
Payments on foreign revolver- B Facility	(8,552)
Payments on acquired debt	(164,083)
Borrowings from swing line of credit, net		(1,874)
Other	(14,380)	(1,490)	(179)
Net cash provided by financing activities	435,725	61,988	236,221
Effect of foreign currency exchange rates on cash	(7,826)	10,600	1,726
Net increase (decrease) in cash	54,456	(1,510)	170,355
Cash and cash equivalents at beginning of year	283,649	285,159	114,804
Cash and cash equivalents at end of year	338,105	283,649	285,159
Supplemental cash flow information
Cash paid for interest	25,886	14,760	14,961
Cash paid for income taxes	$ 99,308	$ 38,169	$ 49,205