Fair Value Measurements - Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	$ 0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale equity securities	216,487	$ 236,167
Total recurring fair value measurements	216,487
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	0
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	216,487
Eurosite Power Inc \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale equity securities	0
Eurosite Power Inc \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale equity securities	216,487
Eurosite Power Inc \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale equity securities	$ 0