Investments - Amortized Cost and Fair Value of Investments by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Amortized cost
Debt securities due within one year	$ 12,481
Debt securities due within one to five years	21,046
Debt securities due within five years or more	9,103
Total	42,630
Fair value
Debt securities due within one year	12,470
Debt securities due within one to five years	21,046
Debt securities due within five years or more	9,076
Total	$ 42,592