Financial Instruments - Amounts of gains/(losses) recognized in income (Details) - Service revenue - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
IRLCs
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 1,342	$ 176	$ 254
Forward sales commitments
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (184)	$ 96	$ (141)

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

Name:	us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration