Business Combinations Business Combinations	3 Months Ended			12 Months Ended
	Mar. 31, 2021 USD ($)	Mar. 31, 2021 USD ($) numberOfConnections	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)
Business Acquisition [Line Items]
Goodwill	$ 69,330,000	$ 69,330,000	$ 69,330,000	$ 69,225,000	$ 69,220,000
Goodwill, Impairment Loss	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Goodwill	69,330,000	69,330,000	69,330,000	69,225,000	$ 69,220,000
Suncadia & T&W Water [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred				$ 38,100,000
Goodwill	18,200,000	18,200,000	18,200,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount	16,500,000	16,500,000	16,500,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	0	0	0
Number of Businesses Acquired				2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Goodwill	18,200,000	$ 18,200,000	$ 18,200,000
Other insignificant acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 1,500,000
Number of Businesses Acquired		1	3