Description of Business, Basis of Presentation, Corporate Transactions, Significant Accounting Policies, and Recent Accounting Pronouncements - Significant Accounting Policies (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of options outstanding, to acquire shares of GWRI common stock (in shares)	631,375	640,796	631,375	640,796
Common share equivalents included in diluted earnings per share (in shares)	14,206		0
Sale of Stock, Number of Shares Issued in Transaction			870,000
Twenty Seventeen Stock Option Grant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of options outstanding, to acquire shares of GWRI common stock (in shares)	385,771	390,796	385,771	390,796
Common share equivalents included in diluted earnings per share (in shares)	32,339	34,406	34,696	11,485
Twenty Nineteen Stock Option Grant [Member] [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of options outstanding, to acquire shares of GWRI common stock (in shares)	245,604	250,000	245,604	250,000