Deferred Tax Assets and Liabilities Result from Differences in Timing of Recognition of Certain Income and Expense Items for Tax and Financial Accounting Purposes (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred income tax assets:
Net operating loss carryforwards	$ 99,021	$ 5,382
Foreign tax credits	19,359	1,909
Compensation	20,668	19,466
Deferred revenue	13,281	13,128
Tax basis in investments	17,723	3,367
Deferred acquisition costs	88	2,480
Deferred alliance costs		8,287
Other	8,356	2,211
Gross deferred income tax assets	178,496	56,230
Less: valuation allowance	(37,941)	(8,135)
Net deferred income tax assets	140,555	48,095
Depreciation and amortization	(57,957)	(8,685)
Total deferred income tax liabilities	(57,957)	(8,685)
Net deferred income taxes	82,598	39,410
Deferred income taxes / liabilities included in the balance sheet are:
Deferred income tax asset - current	34,342	25,944
Deferred income tax asset - noncurrent	63,370	13,466
Deferred income tax liability - current	(174)
Deferred income tax liability - noncurrent	$ (14,940)