Deposit contracts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deposit Contracts, Liabilities [Roll Forward]
Balance, beginning of year	$ 145,342	$ 129,133	$ 104,905
Consideration received	23,884	17,879	22,658
Consideration receivable	10,164	7,390	2,080
Net investment expense (income) allocation	5,879	(1,273)	2,800
Payments	(13,052)	(8,089)	(3,545)
Foreign currency translation	42	302	235
Balance, end of year	$ 172,259	$ 145,342	$ 129,133