Taxation - Reconciliation of effective tax rate (Details)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of effective tax rate (% of income before taxes)
Expected tax rate	0.00%	0.00%	0.00%
Foreign taxes at local expected tax rates	6.50%	14.30%	11.40%
Impact of foreign exchange (losses) gains	(0.50%)	(4.20%)	(3.20%)
Unrecognized tax (benefit) expense	0.20%	(1.20%)	(1.00%)
Tax-exempt income and expenses not deductible	(0.60%)	7.30%	(5.20%)
Foreign branch tax	(1.20%)	(4.10%)	(24.60%)
Valuation allowance	0.70%	(12.30%)	24.80%
Outside basis difference in subsidiary	0.00%	6.70%	0.00%
Other	0.20%	2.90%	1.60%
Actual tax rate	5.30%	9.40%	3.80%

The tax rate applicable to the Company based on its domicile.

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- Definition

The portion of the difference between expected and actual tax rate that relates to gains resulting from fluctuations in, and the treatment of, foreign exchange rates.

+ References

No definition available.

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- Definition

The portion of the difference between the effective income tax rate and domestic statutory income tax rate that can be explained by difference in foreign branch tax rates and tax basis.

+ References

No definition available.

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to either (a) income that is exempt from income taxes or (b) expenses that are not deductible under enacted tax laws.

+ References

No definition available.

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Outside basis difference in subsidiary

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No definition available.

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- Definition

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income tax contingencies. Includes, but not limited to, domestic tax contingency, foreign tax contingency, state and local tax contingency, and other contingencies.

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