Income Taxes Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Limitations on Use	500
Operating loss carryforwards	$ 79,000
Operating Loss Carryforwards, Expiration Date	Jan. 01, 2027
Excess tax benefit from share-based compensation, operating activities	$ 12,700
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, beginning of year	80	$ 65	$ 390
Decreases to tax positions related to prior periods	0	0	(346)
Increases to tax positions related to the current year	40	15	21
Balance, end of year	$ 120	$ 80	$ 65