GUARANTOR CONDENSED CONSOLIDATING FINANCIAL STATEMENTS - CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities		$ 199,617	$ 155,320	$ 162,979
Investing activities:
Capitalization of content databases		(32,514)	(37,566)	(22,239)
Purchases of property and equipment		(15,117)	(21,821)	(26,714)
Issuance of related-party note receivable		(10,000)	0	(9,000)
Investment in subsidiaries		0	0	0
Return of capital from subsidiaries		0	0	0
Net cash used in investing activities		(57,631)	(59,387)	(57,953)
Financing activities:
Member’s capital contributions			26	2,557
Excess tax benefits from stock-based compensation		27	4,063	292
Proceeds from exercise of stock options		0	0	457
Taxes paid related to net share settlement of stock-based awards		0	0	(595)
Proceeds from credit facilities		727,650	0	0
Principal payments on debt		(586,370)	(37,572)	(47,896)
Payment of debt-offering costs		(9,229)		(8,938)
Repayment of intercompany loans payable				0
Return-of-capital distributions	$ (215,000)	(254,401)	(37,610)	0
Payment of contingent consideration		0	(2,900)	0
Capital contribution from parent		0	0	0
Return of capital to parent		0	0	0
Intercompany dividends paid		0	0	0
Net cash used in financing activities		(122,323)	(73,993)	(54,123)
Net increase in cash and cash equivalents		19,663	21,940	50,903
Cash and cash equivalents at beginning of period		108,494	86,554	35,651
Cash and cash equivalents at end of period		128,157	108,494	86,554
Elimination [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities		(216,736)	(218,997)	(7,656)
Investing activities:
Capitalization of content databases		0	0	0
Purchases of property and equipment		0	0	0
Issuance of related-party note receivable		0	0	0
Collection of intercompany loans				(26,200)
Investment in subsidiaries		32,213	25,556	45,944
Return of capital from subsidiaries		(417,309)	(66,860)	(165,566)
Net cash used in investing activities		(385,096)	(41,304)	(145,822)
Financing activities:
Member’s capital contributions			0	0
Excess tax benefits from stock-based compensation		0	0	0
Proceeds from exercise of stock options				0
Taxes paid related to net share settlement of stock-based awards				0
Proceeds from credit facilities		0
Principal payments on debt		0	0	0
Payment of debt-offering costs		0		0
Repayment of intercompany loans payable				26,200
Return-of-capital distributions		0	0
Payment of contingent consideration			0
Capital contribution from parent		(32,213)	(25,556)	(45,944)
Return of capital to parent		417,309	66,860	165,566
Intercompany dividends paid		216,736	218,997	7,656
Net cash used in financing activities		601,832	260,301	153,478
Net increase in cash and cash equivalents		0	0	0
Cash and cash equivalents at beginning of period		0	0	0
Cash and cash equivalents at end of period		0	0	0
Parent [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities		129,619	37,543	342
Investing activities:
Capitalization of content databases		0	0	0
Purchases of property and equipment		0	0	0
Issuance of related-party note receivable		0	0	0
Collection of intercompany loans				0
Investment in subsidiaries		(63)	0	(2,853)
Return of capital from subsidiaries		124,650	0	0
Net cash used in investing activities		124,587	0	(2,853)
Financing activities:
Member’s capital contributions			26	2,557
Excess tax benefits from stock-based compensation		0	0	292
Proceeds from exercise of stock options				0
Taxes paid related to net share settlement of stock-based awards				0
Proceeds from credit facilities		0
Principal payments on debt		0	0	0
Payment of debt-offering costs		0		0
Repayment of intercompany loans payable				0
Return-of-capital distributions		(254,401)	(37,610)
Payment of contingent consideration			0
Capital contribution from parent		0	0	0
Return of capital to parent		0	0	0
Intercompany dividends paid		0	0	0
Net cash used in financing activities		(254,401)	(37,584)	2,849
Net increase in cash and cash equivalents		(195)	(41)	338
Cash and cash equivalents at beginning of period		297	338	0
Cash and cash equivalents at end of period		102	297	338
Issuer [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities		47,087	129,471	(25,037)
Investing activities:
Capitalization of content databases		0	0	0
Purchases of property and equipment		0	0	0
Issuance of related-party note receivable		0	0	0
Collection of intercompany loans				0
Investment in subsidiaries		(32,072)	(25,448)	(42,227)
Return of capital from subsidiaries		72,720	0	144,832
Net cash used in investing activities		40,648	(25,448)	102,605
Financing activities:
Member’s capital contributions			0	0
Excess tax benefits from stock-based compensation		0	0	0
Proceeds from exercise of stock options				0
Taxes paid related to net share settlement of stock-based awards				0
Proceeds from credit facilities		727,650
Principal payments on debt		(586,370)	(37,572)	(47,896)
Payment of debt-offering costs		(9,229)		(8,938)
Repayment of intercompany loans payable				0
Return-of-capital distributions		0	0
Payment of contingent consideration			0
Capital contribution from parent		0	0	499
Return of capital to parent		(219,939)	(66,860)	(17,313)
Intercompany dividends paid		0	0	(3,828)
Net cash used in financing activities		(87,888)	(104,432)	(77,476)
Net increase in cash and cash equivalents		(153)	(409)	92
Cash and cash equivalents at beginning of period		153	562	470
Cash and cash equivalents at end of period		0	153	562
Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities		240,719	211,511	199,246
Investing activities:
Capitalization of content databases		(32,514)	(37,566)	(22,164)
Purchases of property and equipment		(15,083)	(21,547)	(26,597)
Issuance of related-party note receivable		(10,000)	0	(9,000)
Collection of intercompany loans				0
Investment in subsidiaries		0	(60)	(864)
Return of capital from subsidiaries		219,939	66,860	20,734
Net cash used in investing activities		162,342	7,687	(37,891)
Financing activities:
Member’s capital contributions			0	0
Excess tax benefits from stock-based compensation		0	4,063	0
Proceeds from exercise of stock options				457
Taxes paid related to net share settlement of stock-based awards				(595)
Proceeds from credit facilities		0
Principal payments on debt		0	0	0
Payment of debt-offering costs		0		0
Repayment of intercompany loans payable				(26,200)
Return-of-capital distributions		0	0
Payment of contingent consideration			(2,900)
Capital contribution from parent		32,150	25,496	45,080
Return of capital to parent		(197,370)	0	(144,832)
Intercompany dividends paid		(216,736)	(201,529)	(3,828)
Net cash used in financing activities		(381,956)	(174,870)	(129,918)
Net increase in cash and cash equivalents		21,105	44,328	31,437
Cash and cash equivalents at beginning of period		104,690	60,362	28,925
Cash and cash equivalents at end of period		125,795	104,690	60,362
Non-Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities		(1,072)	(4,208)	(3,916)
Investing activities:
Capitalization of content databases		0	0	(75)
Purchases of property and equipment		(34)	(274)	(117)
Issuance of related-party note receivable		0	0	0
Collection of intercompany loans				26,200
Investment in subsidiaries		(78)	(48)	0
Return of capital from subsidiaries		0	0	0
Net cash used in investing activities		(112)	(322)	26,008
Financing activities:
Member’s capital contributions			0	0
Excess tax benefits from stock-based compensation		27	0	0
Proceeds from exercise of stock options				0
Taxes paid related to net share settlement of stock-based awards				0
Proceeds from credit facilities		0
Principal payments on debt		0	0	0
Payment of debt-offering costs		0		0
Repayment of intercompany loans payable				0
Return-of-capital distributions		0	0
Payment of contingent consideration			0
Capital contribution from parent		63	60	365
Return of capital to parent		0	0	(3,421)
Intercompany dividends paid		0	(17,468)	0
Net cash used in financing activities		90	(17,408)	(3,056)
Net increase in cash and cash equivalents		(1,094)	(21,938)	19,036
Cash and cash equivalents at beginning of period		3,354	25,292	6,256
Cash and cash equivalents at end of period		$ 2,260	$ 3,354	$ 25,292