Fair Value Measurement Cash and Cash Equivalents (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Assets, Fair Value Disclosure
Total Assets, Fair Value	$ 12,041	$ 62,024	$ 50,006
Level 1
Assets, Fair Value Disclosure
Total Assets, Fair Value	12,041	62,024	50,006
Level 2
Assets, Fair Value Disclosure
Total Assets, Fair Value	0	0	0
Level 3
Assets, Fair Value Disclosure
Total Assets, Fair Value	0	0	0
Money Market Funds
Assets, Fair Value Disclosure
Cash equivalents	12,041	62,024	50,006
Money Market Funds | Level 1
Assets, Fair Value Disclosure
Cash equivalents	12,041	62,024	50,006
Money Market Funds | Level 2
Assets, Fair Value Disclosure
Cash equivalents	0	0	0
Money Market Funds | Level 3
Assets, Fair Value Disclosure
Cash equivalents	$ 0	$ 0	$ 0