Financial Instruments - Amounts of gains/(losses) recognized in income (Details) - Service revenue - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Interest rate lock commitments
Fair Value, Option, Quantitative Disclosures [Line Items]
Net gain recognized in earnings	$ (142)	$ (11)	$ 1,053	$ 435
Forward sales commitments
Fair Value, Option, Quantitative Disclosures [Line Items]
Net gain recognized in earnings	$ 1,460	$ 3	$ (110)	$ 241