Investments - Amortized Cost and Gross Unrealized Gains and Losses on All Securities (Detail) (Short-term Investments [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 34,014	$ 14,216
Gross Unrealized Gains	1
Gross Unrealized Losses	755	649
Fair Value	33,260	13,567
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,998	2,998
Gross Unrealized Gains	1
Fair Value	3,999	2,998
FDIC Guaranteed certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,560	6,160
Gross Unrealized Losses	5	6
Fair Value	4,555	6,154
Common stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,000	2,000
Gross Unrealized Losses	743	642
Fair Value	1,257	1,358
Corporate notes and bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	23,456	3,058
Gross Unrealized Losses	7	1
Fair Value	$ 23,449	$ 3,057