Fair Value Measurements - Additional Information (Detail) (USD $)	Feb. 09, 2013	Dec. 19, 2012	Dec. 19, 2012 Maximum [Member]	Dec. 19, 2012 First year [Member]	Dec. 19, 2012 Second year [Member]	Feb. 09, 2013 Fair Value, Measurements, Recurring [Member]	Aug. 25, 2012 Fair Value, Measurements, Recurring [Member]
Business Acquisition [Line Items]
Short-term marketable securities						$ 15,028,000	$ 22,515,000
Long-term marketable securities						67,175,000	53,699,000
Acquisition of assets and liabilities		150,000,000
Initial cash payment		115,000,000
Holdback payment for working capital true-ups		5,000,000
Contingent payments, total		30,000,000	30,000,000	10,000,000	30,000,000
Estimated fair value of the performance-based contingent consideration		22,700,000
Contingent liability, current	7,600,000
Contingent liability, non-current	$ 15,400,000