Mortgage Servicing Rights - Changes in the Company's MSRs (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($)
Changes in mortgage servicing rights
Balance at January 1, 2019	$ 48,230
Capitalization	2,181
Amortization	(1,438)
Balance at March 31, 2019	$ 48,973

Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Name:	us-gaap_ServicingAssetAtAmortizedValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant