Significant Accounting Policies (Details)	12 Months Ended
	Mar. 31, 2014 item
Revenue recognition
Number of revenue recognition criteria	4
Pipelines and measurement
Property, plant and equipment
Depreciation rate declining balance method (as a percent)	5.00%
Wells
Property, plant and equipment
Depreciation rate declining balance method (as a percent)	5.00%
Facilities | Minimum
Property, plant and equipment
Depreciation rate declining balance method (as a percent)	5.00%
Facilities | Maximum
Property, plant and equipment
Depreciation rate declining balance method (as a percent)	22.00%
Computer hardware and software
Property, plant and equipment
Depreciation rate declining balance method (as a percent)	30.00%
Office furniture and fixtures
Property, plant and equipment
Depreciation rate declining balance method (as a percent)	20.00%
Other
Property, plant and equipment
Depreciation rate declining balance method (as a percent)	10.00%