Income Taxes - Summary of Income Tax Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, opening balance	$ 1,982	$ 1,736	$ 2,129
Gross increases in tax positions taken in a prior year	77	187	142
Gross increases in tax positions taken in the current year	856	763	309
Lapse of applicable statute of limitations	(366)	(704)	(844)
Unrecognized tax benefits, ending balance	$ 2,549	$ 1,982	$ 1,736