Stock-based Compensation - Summary of Share Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stock-based compensation expense:
Total stock-based compensation expense	$ 688	$ 400
Time-based restricted stock units [Member]
Stock-based compensation expense:
Total stock-based compensation expense	127	109
Performance-based restricted stock units [Member]
Stock-based compensation expense:
Total stock-based compensation expense	$ 561	$ 291