Investments - Summarized Financial Information (Details) - WMES - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Income Statement [Abstract]
Revenue	$ 11,804	$ 13,594	$ 19,915	$ 23,137
Expenses	10,425	10,025	18,179	18,398
WMES net income	1,379	$ 3,569	1,736	$ 4,739
Statement of Financial Position [Abstract]
Total assets	329,540		329,540		$ 322,606
Total liabilities	232,250		232,250		227,052
Total WMES net equity	$ 97,290		$ 97,290		$ 95,554