Other assets - Narratives (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure Abstract
Hosting arrangement service contract implementation cost capitalized	$ 14,500	$ 14,500
Hosting arrangement service contract accumulated amortization	3,700	3,700
Hosting arrangement service contract, net value	10,800	10,800
Hosting arrangement service amortization expense	500	1,000
Other assets
Principal, interest and escrow servicing advances	94,835	94,835	$ 77,800
COVID-19
Other assets
Principal, interest and escrow servicing advances	$ 17,000	$ 17,000