Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flow from operating activities:
Net income	$ 42,862	$ 131,127	$ 117,895
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	150,834	99,831	99,780
Stock-based compensation expense	44,079	11,483	8,386
Income tax benefit related to exercise of stock options	(32,960)	(15,454)	(24,194)
Amortization and write-offs of loan origination costs	8,126	5,839	5,830
Loss on extinguishment of debt	3,954
Loss on sale or disposition of property and equipment	336	687	317
Deferred income taxes	(39,806)	(13,583)	(11,069)
Provision for doubtful accounts	1,137	610	666
Changes in operating assets and liabilities, excluding effects from acquisitions:
Accounts receivable	(12,160)	3,902	814
Prepaid expenses and other current assets	(6,019)	(6,419)	(4,695)
Accounts payable	(5,586)	1,525	(4,032)
Accrued expenses	4,073	10,140	1,695
Income taxes prepaid and payable	11,514	21,560	18,060
Deferred revenue	60,240	1,284	(1,184)
Net cash provided by operating activities	230,624	252,532	208,269
Cash flow from investing activities:
Additions to property and equipment	(13,600)	(15,040)	(11,921)
Proceeds from sale of property and equipment	64	42	67
Cash paid for business acquisitions, net of cash acquired (Note 11)	(2,730,956)	(86,911)	(3,657)
Additions to capitalized software	(4,273)	(3,517)	(2,399)
Net changes in restricted cash	453	983
Net cash used in investing activities	(2,748,312)	(104,443)	(17,910)
Cash flow from financing activities:
Cash received from debt borrowings, net of original issue discount	3,068,075	75,000
Repayments of debt	(903,448)	(212,000)	(239,000)
Proceeds from exercise of stock options	30,092	24,110	27,817
Withholding taxes related to equity award net share settlement	(6,939)
Payment of contingent consideration		(500)
Income tax benefit related to exercise of stock options	32,960	15,454	24,194
Proceeds from common stock issuance, net	717,802
Purchase of common stock for treasury		(11,223)	(943)
Payment of fees related to refinancing activities	(46,025)	(512)	(1,917)
Dividends paid on common stock	(45,451)	(10,494)
Net cash provided by (used in) financing activities	2,847,066	(120,165)	(189,849)
Effect of exchange rate changes on cash and cash equivalents	(4,796)	(2,817)	(2,200)
Net increase in cash and cash equivalents	324,582	25,107	(1,690)
Cash and cash equivalents, beginning of period	109,577	84,470	86,160
Cash and cash equivalents, end of period	434,159	109,577	84,470
Supplemental disclosure of cash paid for:
Interest	42,221	21,330	36,551
Income taxes, net of refunds	$ 42,210	$ 33,414	$ 21,584