Segment Information (Company's Segment Information, Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Total assets	$ 14,236,485	$ 13,705,277
Other [Member]
Segment Reporting Information [Line Items]
Total assets	186,510	563,736
Regulated [Member] | Water [Member]
Segment Reporting Information [Line Items]
Total assets	8,301,201	7,838,034
Regulated [Member] | Natural Gas [Member]
Segment Reporting Information [Line Items]
Total assets	$ 5,748,774	$ 5,303,507