Income taxes - Reconciliation of the US statutory income tax rate (Details) - USD ($) $ in Millions		12 Months Ended
Jan. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income taxes
Statutory Federal and Provincial tax rate in Canada		27.00%	26.00%	26.00%
Expected income tax expense (benefit) at statutory rate		$ (358)	$ (27)	$ 17
Impact of US Tax Cuts and Jobs Act of 2017			26
Change in statutory tax rates		23	(1)
Non-deductible expenses		1	10	2
Foreign exchange differences		(44)	(1)	1
Change in valuation allowance		207	(123)	13
Changes in uncertain tax position		(20)	(14)	(4)
Foreign earnings subject to different tax rates		(27)	(13)	(10)
Research and development tax credits		(18)	(19)	(20)
Non-deductible goodwill impairment		172
Other		2
Income tax benefit		$ (62)	$ (162)	$ (1)
Effective income tax rate		4.70%	155.80%	(1.50%)
US federal corporate tax rate	21.00%		35.00%

Percentage of foreign federal statutory tax rate applicable to pretax income (loss).

No definition available.

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Namespace Prefix:	maxr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations, attributable to the total of all provisions of the Tax Cuts and Jobs Act of 2017.

+ References

No definition available.