Short-Term and Long-Term Investments - Summary of Available-for-Sale Securities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 6,710	$ 6,820
Gross Unrealized Gains	1	6
Gross unrealized losses	1,036	1,175
Estimated Fair Value	5,675	5,651
Failed Auction Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	6,000	6,000
Gross unrealized losses	1,036	1,175
Estimated Fair Value	4,964	4,825
Brokered Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	710	820
Gross Unrealized Gains	1	6
Estimated Fair Value	$ 711	$ 826