Fair Value Measurements - Liabilities Carried at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Other accrued expenses and other current liabilities:
Accrued acquisition payments	$ 80,404	$ 77,532
Fair value measured on recurring basis [Member] | Accrued acquisition payments [Member]
Other accrued expenses and other current liabilities:
Accrued acquisition payments	1,956	2,178
Other long-term liabilities:
Accrued acquisition payments, long-term portion	724	2,286
Total liabilities carried at fair value	2,680	4,464
Level 2 [Member] | Fair value measured on recurring basis [Member] | Accrued acquisition payments [Member]
Other accrued expenses and other current liabilities:
Accrued acquisition payments	657	789
Other long-term liabilities:
Accrued acquisition payments, long-term portion		595
Total liabilities carried at fair value	657	1,384
Level 3 [Member] | Fair value measured on recurring basis [Member] | Accrued acquisition payments [Member]
Other accrued expenses and other current liabilities:
Accrued acquisition payments	1,299	1,389
Other long-term liabilities:
Accrued acquisition payments, long-term portion	724	1,691
Total liabilities carried at fair value	$ 2,023	$ 3,080