Income Taxes - Unrecognized Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Gross unrecognized tax benefits at beginning of year	$ 5,011	$ 7,024	$ 14,824
Increases in tax positions for prior years	22	859	0
Decreases in tax positions for prior years	(1,684)	(96)	(525)
Increases in tax positions for current years	336	0	0
Decreases from lapse in statute of limitations	(1,020)	(2,776)	(7,275)
Gross unrecognized tax benefits at end of year	$ 2,665	$ 5,011	$ 7,024