Commitments and Contingencies - Additional Information (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Commitments And Contingencies Disclosure [Line Items]
Contingent consideration	$ 78,611,000	$ 80,476,000
Uncertain tax positions	21,000,000	21,600,000
All 2013 Acquisitions [Member]
Commitments And Contingencies Disclosure [Line Items]
Contingent consideration	49,200,000	83,100,000
Uncertain tax positions	13,400,000	13,400,000
Indemnification asset recorded	$ 51,100,000	$ 51,100,000