GUARANTOR CONDENSED CONSOLIDATING FINANCIAL STATEMENTS - CONDENSED CONSOLIDATING BALANCE SHEETS (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 128,157	$ 108,494	$ 86,554	$ 35,651
Restricted cash	2,412	49,086
Accounts receivable, net of allowances	13,624	11,241
Prepaid expenses	12,228	9,830
Other current assets	6,288	1,813
Intercompany receivables	0	0
Total current assets	162,709	180,464
Property and equipment, net	54,795	37,106
Content databases, net	282,281	282,815
Intangible assets, net	159,736	269,054
Goodwill	948,283	948,283
Investment in subsidiary	0	0
Other assets	13,956	3,175
Total assets	1,621,760	1,720,897
Current liabilities:
Accounts payable	13,120	11,515
Accrued expenses	50,459	47,029
Acquisition-related liabilities	2,412	49,086
Deferred revenues	171,822	145,010
Current portion of long-term debt	7,087	46,537
Intercompany payables	0	0
Total current liabilities	244,900	299,177
Long-term debt, net	989,256	799,403
Deferred income taxes	59,809	110,184
Other long-term liabilities	46,877	16,406
Total liabilities	1,340,842	1,225,170
Total member’s interests	280,918	495,727	540,697	609,346
Total liabilities and member’s interests	1,621,760	1,720,897
Elimination [Member]
Current assets:
Cash and cash equivalents	0	0	0	0
Restricted cash	0	0
Accounts receivable, net of allowances	0	0
Prepaid expenses	0	0
Other current assets	0	0
Intercompany receivables	(1,380)	(3,752)
Total current assets	(1,380)	(3,752)
Property and equipment, net	0	0
Content databases, net	0	0
Intangible assets, net	0	0
Goodwill	0	0
Investment in subsidiary	(1,703,400)	(2,198,349)
Other assets	0	0
Total assets	(1,704,780)	(2,202,101)
Current liabilities:
Accounts payable	0	0
Accrued expenses	0	0
Acquisition-related liabilities	0	0
Deferred revenues	0	0
Current portion of long-term debt	0	0
Intercompany payables	(1,380)	(3,752)
Total current liabilities	(1,380)	(3,752)
Long-term debt, net	0	0
Deferred income taxes	0	0
Other long-term liabilities	0	0
Total liabilities	(1,380)	(3,752)
Total member’s interests	(1,703,400)	(2,198,349)
Total liabilities and member’s interests	(1,704,780)	(2,202,101)
Parent [Member]
Current assets:
Cash and cash equivalents	102	297	338	0
Restricted cash	0	0
Accounts receivable, net of allowances	0	0
Prepaid expenses	0	0
Other current assets	0	0
Intercompany receivables	57	46
Total current assets	159	343
Property and equipment, net	0	0
Content databases, net	0	0
Intangible assets, net	0	0
Goodwill	0	0
Investment in subsidiary	282,222	496,781
Other assets	0	0
Total assets	282,381	497,124
Current liabilities:
Accounts payable	0	0
Accrued expenses	0	0
Acquisition-related liabilities	0	0
Deferred revenues	0	0
Current portion of long-term debt	0	0
Intercompany payables	66	0
Total current liabilities	66	0
Long-term debt, net	0	0
Deferred income taxes	0	0
Other long-term liabilities	0	0
Total liabilities	66	0
Total member’s interests	282,315	497,124
Total liabilities and member’s interests	282,381	497,124
Issuer [Member]
Current assets:
Cash and cash equivalents	0	153	562	470
Restricted cash	0	45,280
Accounts receivable, net of allowances	0	0
Prepaid expenses	64	0
Other current assets	0	0
Intercompany receivables	0	0
Total current assets	64	45,433
Property and equipment, net	0	0
Content databases, net	0	0
Intangible assets, net	0	0
Goodwill	0	0
Investment in subsidiary	1,209,851	1,278,254
Other assets	1,090	318
Total assets	1,211,005	1,324,005
Current liabilities:
Accounts payable	0	60
Accrued expenses	1,377	7,051
Acquisition-related liabilities	0	45,280
Deferred revenues	0	0
Current portion of long-term debt	7,087	46,537
Intercompany payables	0	0
Total current liabilities	8,464	98,928
Long-term debt, net	989,256	799,403
Deferred income taxes	0	0
Other long-term liabilities	0	0
Total liabilities	997,720	898,331
Total member’s interests	213,285	425,674
Total liabilities and member’s interests	1,211,005	1,324,005
Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	125,795	104,690	60,362	28,925
Restricted cash	2,412	3,806
Accounts receivable, net of allowances	13,363	6,690
Prepaid expenses	12,019	9,668
Other current assets	6,153	1,623
Intercompany receivables	135	2,895
Total current assets	159,877	129,372
Property and equipment, net	54,415	36,551
Content databases, net	281,566	281,998
Intangible assets, net	159,736	269,054
Goodwill	947,613	947,563
Investment in subsidiary	211,201	423,266
Other assets	12,583	2,617
Total assets	1,826,991	2,090,421
Current liabilities:
Accounts payable	12,649	11,026
Accrued expenses	47,860	35,747
Acquisition-related liabilities	2,412	3,806
Deferred revenues	171,797	144,969
Current portion of long-term debt	0	0
Intercompany payables	1,205	825
Total current liabilities	235,923	196,373
Long-term debt, net	0	0
Deferred income taxes	59,809	110,220
Other long-term liabilities	46,748	16,406
Total liabilities	342,480	322,999
Total member’s interests	1,484,511	1,767,422
Total liabilities and member’s interests	1,826,991	2,090,421
Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	2,260	3,354	$ 25,292	$ 6,256
Restricted cash	0	0
Accounts receivable, net of allowances	261	4,551
Prepaid expenses	145	162
Other current assets	135	190
Intercompany receivables	1,188	811
Total current assets	3,989	9,068
Property and equipment, net	380	555
Content databases, net	715	817
Intangible assets, net	0	0
Goodwill	670	720
Investment in subsidiary	126	48
Other assets	283	240
Total assets	6,163	11,448
Current liabilities:
Accounts payable	471	429
Accrued expenses	1,222	4,231
Acquisition-related liabilities	0	0
Deferred revenues	25	41
Current portion of long-term debt	0	0
Intercompany payables	109	2,927
Total current liabilities	1,827	7,628
Long-term debt, net	0	0
Deferred income taxes	0	(36)
Other long-term liabilities	129	0
Total liabilities	1,956	7,592
Total member’s interests	4,207	3,856
Total liabilities and member’s interests	$ 6,163	$ 11,448