Investments - Amortized Cost and Gross Unrealized Gains and Losses on All Securities (Detail) - Short-term Investments [Member] - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 12,677	$ 20,578
Gross Unrealized Gains	2
Gross Unrealized Losses	3	16
Fair Value	12,676	20,562
FDIC Guaranteed Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,880	2,120
Gross Unrealized Gains	2
Gross Unrealized Losses		2
Fair Value	2,882	2,118
Corporate Notes/Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,797	18,458
Gross Unrealized Losses	3	14
Fair Value	$ 9,794	$ 18,444