CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Unrealized holding gain arising during the period, tax	$ 1,581	$ (2,931)	$ (3,535)
Reclassifications to net loss, tax	(681)	0	0
Unrealized holding gain (loss) arising during the period, tax	0	(1,214)	789
Reclassifications to net loss, tax	$ 0	$ (365)	$ (28)