Discontinued operations - Mexico project development- Narratives (Details) $ / shares in Units, gal in Millions					1 Months Ended						3 Months Ended	6 Months Ended
	Aug. 28, 2020 USD ($)	Aug. 28, 2020 MXN ($)	Jun. 29, 2020	Aug. 22, 2016	Aug. 22, 2016 gal	Nov. 30, 2015 gal	Feb. 28, 2014 USD ($)	May 31, 2013 USD ($) $ / shares	Feb. 29, 2012 USD ($)	May 31, 2010 gal	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2021 USD ($) ha	Dec. 31, 2019	Feb. 28, 2018	Jan. 31, 2018
Schedule of Investments [Line Items]
Land													$ 21,100,000
Period Required To Operate And Maintain Plant And Aqueduct				37 years
Number of days to submit list of non-recoverable expenses made			20 days
Amount of non-recoverable expenses	$ 51,144,525	$ 137,333,114
Impairment loss on long-lived assets											$ (3,000,000.0)
Adjustment to reduce operating lease right of use assets											2,600,000	$ 2,600,000
Adjustment to reduce operating lease liabilities											$ 2,200,000	2,200,000
Payments For Option Exercised							$ 1,000,000.0
Share Price | $ / shares								$ 1
Aguas de Rosarito S.A.P.I. de C.V [Member]
Schedule of Investments [Line Items]
Equity Method Investment, Ownership Percentage													50.00%
Option agreement [Member]
Schedule of Investments [Line Items]
Payments To Enter Option Agreement									$ 300,000
NSC Agua [Member]
Schedule of Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners										50.00%
Total Voting Interest Percentage After Conversion Of Loan										99.99%
Total Percentage Of Ownership Interest In An Acquired Company																99.99%
Seawater Reverse Osmosis Desalination Plant Per Day Processing Capacity | gal					100					100
Area of Land | ha													20.1
Equity Method Investment, Ownership Percentage													50.00%
Period in which construction must be completed				36 months
Payments for land and rights of way held for development												$ 3,000,000.0
Payments For Option Exercised							$ 1,000,000.0
Percentage of Voting Interest Acquired through Option Agreement							25.00%	25.00%
NSC Agua [Member] | Aguas de Rosarito S.A.P.I. de C.V [Member]
Schedule of Investments [Line Items]
Equity Method Investment, Ownership Percentage														99.60%	0.40%
NSC Agua [Member] | First Phase [Member]
Schedule of Investments [Line Items]
Seawater Reverse Osmosis Desalination Plant Per Day Processing Capacity | gal					50	50
NSC Agua [Member] | Second Phase [Member]
Schedule of Investments [Line Items]
Seawater Reverse Osmosis Desalination Plant Per Day Processing Capacity | gal					50	50
NSC Agua [Member] | Option agreement [Member]
Schedule of Investments [Line Items]
Total Voting Interest Percentage After Conversion Of Loan								99.99%
Repayment of inter-company loan payable								$ 5,700,000
Option Agreement Expiration Date									Feb. 07, 2014