Other assets and other liabilities - Summary of Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Assets And Other Liabilities [Abstract]
Deferred compensation	$ 3,836	$ 5,301
Accrued payroll	8,026	11,018
Mortgage servicing escrows	4,441	3,341
Mortgage buyback reserve	3,273	3,386
Accrued interest	5,015	1,504
Derivatives (See Note 16)	11,637	1,699
Deferred tax liability (See Note 13)	16,663	11,858
Right to repurchase GNMA loans serviced (See Note 1)	0	43,035
FHLB lender risk account guaranty	2,646	0
Other liabilities	9,877	37,852
Total other liabilities	$ 65,414	$ 118,994