Fair Value Measurements (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands | Jun. 30, 2017 | Dec. 31, 2016 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | $ 9,814 | $ 13,634 |
Available for Sale Securities | 63,624 | 31,743 |
Assets measured at fair value | 73,571 | 45,377 |
Total liabilities measured at fair value | | (38) |
Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 7,816 | 9,635 |
Available for Sale Securities | 0 | 0 |
Assets measured at fair value | 7,816 | 9,635 |
Total liabilities measured at fair value | | 0 |
Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 1,998 | 3,999 |
Available for Sale Securities | 63,624 | 31,743 |
Assets measured at fair value | 65,755 | 35,742 |
Total liabilities measured at fair value | | (38) |
Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 0 | 0 |
Available for Sale Securities | 0 | 0 |
Assets measured at fair value | 0 | 0 |
Total liabilities measured at fair value | | 0 |
Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 7,816 | 9,635 |
Money market funds | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 7,816 | 9,635 |
Money market funds | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 0 | 0 |
Money market funds | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 0 | 0 |
Commercial paper | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 1,998 | 3,999 |
Available for Sale Securities | 11,478 | |
Commercial paper | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 0 | 0 |
Available for Sale Securities | 0 | |
Commercial paper | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 1,998 | 3,999 |
Available for Sale Securities | 11,478 | |
Commercial paper | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash Equivalents | 0 | 0 |
Available for Sale Securities | 0 | |
Certificates of deposit | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 19,126 | 22,820 |
Certificates of deposit | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 0 | 0 |
Certificates of deposit | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 19,126 | 22,820 |
Certificates of deposit | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 0 | 0 |
Corporate bonds | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 26,024 | 6,922 |
Corporate bonds | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 0 | 0 |
Corporate bonds | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 26,024 | 6,922 |
Corporate bonds | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 0 | 0 |
U.S. government bonds | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 6,996 | 2,001 |
U.S. government bonds | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 0 | 0 |
U.S. government bonds | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 6,996 | 2,001 |
U.S. government bonds | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available for Sale Securities | 0 | 0 |
Interest rate swap contract | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Interest rate swap contract | 133 | |
Fair value of liability derivatives | | (38) |
Interest rate swap contract | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Interest rate swap contract | 0 | |
Fair value of liability derivatives | | 0 |
Interest rate swap contract | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Interest rate swap contract | 133 | |
Fair value of liability derivatives | | (38) |
Interest rate swap contract | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Interest rate swap contract | $ 0 | |
Fair value of liability derivatives | | $ 0 |