Investments - Amortized Cost and Gross Unrealized Gains and Losses on All Securities (Detail) - Short-term Investments [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 13,214	$ 20,578
Gross Unrealized Gains	2
Gross Unrealized Losses	8	16
Fair Value	13,208	20,562
FDIC Guaranteed Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,360	2,120
Gross Unrealized Gains	2
Gross Unrealized Losses		2
Fair Value	3,362	2,118
Corporate Notes/Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,854	18,458
Gross Unrealized Losses	8	14
Fair Value	$ 9,846	$ 18,444