Description of Business, Basis of Presentation, Corporate Transactions, Significant Accounting Policies, and Recent Accounting Pronouncements - Significant Accounting Policies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of options outstanding, to acquire shares of GWRI common stock (in shares)	633,000	498,000	740,000
Common share equivalents included in diluted earnings per share (in shares)	14,974	38,928
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options	$ 600,000	$ 14,000