Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Operating activities
Net income	$ 362,431	$ 368,707		$ 284,501
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	30,462	21,097		16,885
Stock-based compensation	90,122	37,649		26,676
Provision for losses on accounts receivable	24,629	24,412		18,867
Amortization of deferred financing costs and discounts	7,049	2,796		3,276
Loss on extinguishment of debt		15,764
Amortization of intangible assets	159,740	86,149		49,313
Amortization of premium on receivables	3,250	3,259		3,263
Deferred income taxes	30,626	41,716		(5,453)
Equity method investment loss	57,668	8,586
Other non-cash operating expenses	(4,242)	(27,501)
Changes in operating assets and liabilities (net of acquisitions):
Restricted cash	(35,676)	6,625		5,430
Accounts receivable	40,017	246,465		(45,005)
Prepaid expenses and other current assets	(12,564)	2,820		(74)
Other assets	(2,524)	12,455		38,906
Excess tax benefits related to stock-based compensation	(26,427)	(56,790)		(32,535)
Accounts payable, accrued expenses and customer deposits	30,023	(185,875)		11,635
Net cash provided by operating activities	754,584	608,334		375,685
Investing activities
Acquisitions, net of cash acquired	(57,539)	(2,567,017)	[1]	(728,343)
Purchases of property and equipment	(41,875)	(27,070)		(20,785)
Net cash used in investing activities	(99,414)	(2,594,087)		(749,128)
Financing activities
Excess tax benefits related to stock-based compensation	26,427	56,790		32,535
Proceeds from issuance of common stock	19,926	29,641		30,438
Borrowings on securitization facility, net	(61,000)	326,000		51,000
Deferred financing costs paid		(43,943)		(1,970)
Proceeds from notes payable		2,320,000
Principal payments on notes payable	(103,500)	(546,875)		(28,125)
Payments on acquired debt				(164,083)
Borrowings from swing line of credit, net	(546)	4,990
Payment of contingent consideration	(42,177)
Other	(377)	(731)		(14,380)
Net cash (used in) provided by financing activities	(648,065)	2,162,265		435,725
Effect of foreign currency exchange rates on cash	(37,022)	(37,548)		(7,826)
Net (decrease) increase in cash	(29,917)	138,964		54,456
Cash and cash equivalents, beginning of year	477,069	338,105		283,649
Cash and cash equivalents, end of year	447,152	477,069		338,105
Supplemental cash flow information
Cash paid for interest	72,537	29,098		25,886
Cash paid for income taxes	83,380	79,124		99,308
Revolving A Facility [Member]
Financing activities
Borrowings from revolver and foreign revolver facilities		807,330		783,663
Payments on revolver and foreign revolver facilities	$ (486,818)	(783,600)		(261,516)
Revolving B Facility [Member]
Financing activities
Borrowings from revolver and foreign revolver facilities				16,715
Payments on revolver and foreign revolver facilities		$ (7,337)		$ (8,552)

[1] Amounts reported in acquisitions and investment, net of cash acquired, includes debt assumed and immediately repaid in acquisitions.