Investments and Fair Value Measurements - Schedule of Maturity Profile of Investments (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Held-to-maturity due within one year	$ 0	$ 0
Held-to-maturity due one year through five years	8,368	8,369
Held-to-maturity due five years through ten years	2,836	3,127
Held-to-maturity due over ten years	11,377	12,193
Held-to-maturity cost or amortized cost	$ 22,581	$ 23,689