Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 56,341	$ 37,820
Unrecognized tax benefits	1,101	$ 343	$ 161	$ 0
Uncertain tax positions that would impact the effective tax rate	57
Domestic Tax Authority | Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, Sec. 382 limitation	125,100
Operating loss carryforwards, expected to be unrealized	420
Gross operating loss carryforwards	4,200
Operating loss carryforwards	120,900
State and Local Jurisdiction | Arizona Department of Revenue
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 102,500