Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Loss Contingencies [Line Items]
Accrual for the probable payment of pending claims	$ 19,026,000
Operating leases rent expenses	10,349,000	9,184,000	5,553,000
Total future minimum lease obligation	7,337,000
Future minimum lease obligation payment period	6 years
Fair Value, Inputs, Level 3
Loss Contingencies [Line Items]
Fair value of contingent purchase price commitments	$ 12,701,000	$ 6,874,000