Income Taxes - Significant Components of Deferred Income Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Components Of Deferred Income Tax Assets And Liabilities [Line Items]
Allowance for uncollectible accounts	$ 48,178	$ 42,425
Reserves and accruals	62,708	52,519
Stock-based compensation	14,354	16,457
Net operating loss carryforward	10,933	6,385
Property and equipment	1,524	1,310
Other	1,461	446
Total deferred tax assets	139,158	119,542
Amortization	(214,968)	(162,399)
Accrual to cash adjustment	(38,524)	(37,818)
Other	(192)
Total deferred tax liabilities	(253,684)	(200,217)
Net deferred tax (liability) asset	(114,526)	(80,675)
Total deferred tax assets	(139,158)	(119,542)
Amortization	(214,968)	(162,399)
Accrual to cash adjustment	(38,524)	(37,818)
Other	(192)
Total deferred tax liabilities	(253,684)	(200,217)
Net deferred tax (liability) asset	(114,526)	(80,675)
Total deferred tax liabilities	253,684	200,217
Net deferred tax (liability) asset	(114,526)	(80,675)
Current [Member]
Components Of Deferred Income Tax Assets And Liabilities [Line Items]
Allowance for uncollectible accounts	48,178	42,425
Reserves and accruals	26,066	18,341
Stock-based compensation	8,346	3,628
Net operating loss carryforward	1,504	3,744
Other	583	446
Total deferred tax assets	84,677	68,584
Accrual to cash adjustment	(38,524)	(37,818)
Other	(192)
Total deferred tax liabilities	(38,716)	(37,818)
Net deferred tax (liability) asset	45,961	30,766
Total deferred tax assets	(84,677)	(68,584)
Accrual to cash adjustment	(38,524)	(37,818)
Other	(192)
Total deferred tax liabilities	(38,716)	(37,818)
Net deferred tax (liability) asset	45,961	30,766
Total deferred tax liabilities	38,716	37,818
Net deferred tax (liability) asset	45,961	30,766
Non-Current [Member]
Components Of Deferred Income Tax Assets And Liabilities [Line Items]
Reserves and accruals	36,642	34,178
Stock-based compensation	6,008	12,829
Net operating loss carryforward	9,429	2,641
Property and equipment	1,524	1,310
Other	878
Total deferred tax assets	54,481	50,958
Amortization	(214,968)	(162,399)
Total deferred tax liabilities	(214,968)	(162,399)
Net deferred tax (liability) asset	(160,487)	(111,441)
Total deferred tax assets	(54,481)	(50,958)
Amortization	(214,968)	(162,399)
Total deferred tax liabilities	(214,968)	(162,399)
Net deferred tax (liability) asset	(160,487)	(111,441)
Total deferred tax liabilities	214,968	162,399
Net deferred tax (liability) asset	$ (160,487)	$ (111,441)