Investments - Amortized Cost and Gross Unrealized Gains and Losses on All Securities (Detail) (Short-term Investments [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 27,575	$ 14,216
Gross Unrealized Gains	267
Gross Unrealized Losses	14	649
Fair Value	27,828	13,567
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,998
Fair Value		2,998
FDIC Guaranteed Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,040	6,160
Gross Unrealized Losses	4	6
Fair Value	4,036	6,154
Common Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,000	2,000
Gross Unrealized Gains	267
Gross Unrealized Losses		642
Fair Value	2,267	1,358
Corporate Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	21,535	3,058
Gross Unrealized Losses	10	1
Fair Value	$ 21,525	$ 3,057