Summarizes Cost And Estimated Fair Value Of Short Term Fixed Income Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Jan. 01, 2016
Fair Value Measurements [Line Items]
Due within one year, Amortized Cost	$ 7,994
Due between one and two years, Amortized Cost	44,000
Total Amortized Cost	51,994
Due within one year, Estimated Fair Value	8,003
Due between one and two years, Estimated Fair Value	43,990
Total Estimated Fair Value	$ 51,993	$ 45,842