Reinsurance - Ceded credit risk (Details) - Reinsurance recoverable for paid and unpaid losses - Reinsurer concentration risk	6 Months Ended	12 Months Ended
Jun. 30, 2020	Dec. 31, 2019
AM Best, A minus or better
Ceded Credit Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%
ARL and ARC \| AM Best, A plus Rating
Ceded Credit Risk [Line Items]
Concentration risk, percentage	44.00%	47.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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