Investments - Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 66,682	$ 80,260
Net Unrealized Gains (Losses)	(1)	(81)
Fair Value/Net Carrying Value	66,681	80,179
Cash and Cash Equivalents	28,382	5,070
Investments	38,299	75,109
Commercial paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	17,852	28,845
Fair Value/Net Carrying Value	17,852	28,845
Cash and Cash Equivalents		999
Investments	17,852	27,846
Corporate debt securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	17,935	45,911
Net Unrealized Gains (Losses)	1	(81)
Fair Value/Net Carrying Value	17,936	45,830
Investments	17,936	45,830
Money market funds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	28,382	4,071
Fair Value/Net Carrying Value	28,382	4,071
Cash and Cash Equivalents	28,382	4,071
Municipal bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,513	1,433
Net Unrealized Gains (Losses)	(2)
Fair Value/Net Carrying Value	2,511	1,433
Investments	$ 2,511	$ 1,433

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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