Fair Value Measurements - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets:
Total	$ 4,543	$ 4,715
Level 1
Assets:
Total
Level 2
Assets:
Total	4,543	4,715
Level 3
Assets:
Total
Corporate bonds and notes
Assets:
Total	1,832	2,881
Corporate bonds and notes | Level 1
Assets:
Total
Corporate bonds and notes | Level 2
Assets:
Total	1,832	2,881
Corporate bonds and notes | Level 3
Assets:
Total
Municipal bonds
Assets:
Total	2,711	1,834
Municipal bonds | Level 1
Assets:
Total
Municipal bonds | Level 2
Assets:
Total	2,711	1,834
Municipal bonds | Level 3
Assets:
Total