Fair Value Measurements - Activity of Level 3 Inputs Measured on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Ending Balance	$ 23,351	$ 14,520
Deferred development costs [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers in / (out) of Level 3	6,418	12,233
Deferred payment contingency [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers in / (out) of Level 3	(2,287)	2,287
Other long term liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers in / (out) of Level 3	$ 4,700