Income Taxes Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Interest accrued	$ 800	$ 200
Penalties expense	400	200
Decrease in unrecognized tax benefits is reasonably possible	200
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	9,207	7,518	$ 4,883
Increases in uncertain tax benefits as a result of tax positions taken in a prior year	287		206
Increases in uncertain tax benefits as a result of tax positions taken in the current year	1,367	1,845	2,429
Decreases in uncertain tax benefits from a lapse of applicable statute of limitations	(233)	(156)
Decreases in uncertain tax benefits as a result of tax positions taken in a prior year	(2,028)
Ending balance	$ 8,600	$ 9,207	$ 7,518