Summary of Significant Accounting Policies (Details) $ in Thousands	6 Months Ended
Jun. 30, 2019 USD ($) Institution	Dec. 31, 2018 USD ($)
Concentration of Credit Risk and Others Risks and Uncertainties [Abstract]
Number of financial institutions holding company's cash \| Institution	2
Other Assets [Abstract]
Lease term	10 years
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Adjusted Cost	$ 4,155	$ 7,611
Adjusted Cost	3,417	4,366
Unrealized Gains	1	0
Unrealized Losses	0	0
Fair Value	3,418	4,366
Adjusted Cost	6,926	9,414
Fair Value	6,927	9,414
Investments Available for Sale	3,418	4,366
Cash [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Adjusted Cost	3,509	5,048
Fair Value	3,509	5,048
Cash and Cash Equivalents	3,509	5,048
Mutual Funds [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Adjusted Cost	646	1,107
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	646	1,107
Investments Available for Sale	646	1,107
U.S. Agency Securities [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Adjusted Cost	2,771	3,259
Unrealized Gains	1	0
Unrealized Losses	0	0
Fair Value	2,772	3,259
Investments Available for Sale	2,772	3,259
Recurring [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value	4,155	7,611
Fair Value	2,772	1,803
Cash and Cash Equivalents	4,155	7,611
Investments Available for Sale	2,772	1,803
Recurring [Member] \| Cash [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value	3,509	5,048
Cash and Cash Equivalents	3,509	5,048
Recurring [Member] \| Level 1 [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value	646	2,563
Fair Value	2,772	1,803
Cash and Cash Equivalents	646	2,563
Investments Available for Sale	2,772	1,803
Recurring [Member] \| Level 1 [Member] \| Mutual Funds [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value	646	1,107
Fair Value	0	0
Cash and Cash Equivalents	646	1,107
Investments Available for Sale	0	0
Recurring [Member] \| Level 1 [Member] \| U.S. Agency Securities [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value	0	1,456
Fair Value	2,772	1,803
Cash and Cash Equivalents	0	1,456
Investments Available for Sale	2,772	$ 1,803
2013 to 2016 [Member]
Deferred Revenue [Abstract]
Total contractual payments received	$ 10,000

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