Allowance for expected credit losses - Reinsurance recoverable (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Credit Loss [Abstract]
Balance at beginning of period	$ 170,974
Balance at end of period	197,458
Deferred tax asset	25
Allowance for Expected Credit Losses - Reinsurance Recoverables
Balance at beginning of period	0
Cumulative effect of adoption of updated accounting guidance for credit losses at January 1, 2020	297	[1]
Current period change for expected credit losses	0
Write-offs charged against the allowance	0
Balance at end of period	$ 297

[1] The allowance for credit losses is gross of deferred tax of $25 thousand.