Short-Term and Long-Term Investments - Summary of Available-for-Sale Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 6,730	$ 6,820
Gross Unrealized Gains	3	6
Gross unrealized losses	1,096	1,175
Estimated Fair Value	5,637	5,651
Failed Auction Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	6,000	6,000
Gross unrealized losses	1,096	1,175
Estimated Fair Value	4,904	4,825
Brokered Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	730	820
Gross Unrealized Gains	3	6
Estimated Fair Value	$ 733	$ 826