Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Federal statutory tax rate	35.00%	35.00%	35.00%
Valuation allowance	$ 3,321	$ 1,552	$ 0
Alternative minimum tax credits, non-expiring	800
Excess tax benefit from stock option exercise	2,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	4,200
Federal Tax Authority
Operating Loss Carryforwards [Line Items]
Alternative minimum tax credits, non-expiring	$ 11,200