Fair Value Measurements (Financial Instruments Measured at Fair Value on a Recurring Basis) (Detail) (Recurring [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Assets:
Money market funds	$ 121,095	$ 163,368
Certificate of deposit	26,128	0
Corporate debt securities	13,572	44,877
Commercial paper	0	8,996
U.S. government sponsored agency bonds	0	2,015
U.S. treasury securities	0	5,513
Foreign currency hedge contracts	0	6,838
Total	160,795	231,607
Liabilities:
Foreign currency hedge contracts	7,581	9,783
Fair Value Level 1 [Member]
Assets:
Money market funds	121,095	163,368
Certificate of deposit	0	0
Corporate debt securities	0	0
Commercial paper	0	0
U.S. government sponsored agency bonds	0	2,015
U.S. treasury securities	0	5,513
Foreign currency hedge contracts	0	0
Total	121,095	170,896
Liabilities:
Foreign currency hedge contracts	0	0
Fair Value Level 2 [Member]
Assets:
Money market funds	0	0
Certificate of deposit	26,128	0
Corporate debt securities	13,572	44,877
Commercial paper	0	8,996
U.S. government sponsored agency bonds	0	0
U.S. treasury securities	0	0
Foreign currency hedge contracts	0	6,838
Total	39,700	60,711
Liabilities:
Foreign currency hedge contracts	$ 7,581	$ 9,783