Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings - Summary of amounts outstanding under master netting agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Offsetting [Abstract]
Repurchase agreements / reverse repurchase agreements, gross amounts of recognized assets		$ 50,000
Repurchase agreements / reverse repurchase agreements, gross amounts offset on balance sheet		(50,000)
Repurchase agreements / reverse repurchase agreements, net asset balance		0
Repurchase agreements / reverse repurchase agreements, gross amounts not offset in balance sheet - financial instruments		0
Repurchase agreements/ reverse repurchase agreements, gross amounts not offset in balance sheet - collateral received		0
Repurchase agreements / reverse repurchase agreements, net amount		0
Derivative, gross amounts of recognized assets	$ 35,007	24,705
Derivative, gross amounts offset on balance sheet	0	0
Derivatives, net asset balance	35,007	24,705
Derivatives, gross amounts not offset in balance sheet - financial instruments	(401)	(973)
Derivatives, gross amounts not offset in balance sheet - collateral received	0	(8,029)
Derivatives asset, net amount	34,606	15,703
Offsetting assets, gross amounts of recognized assets	35,007	74,705
Offsetting assets, gross amounts offset on balance sheet	0	(50,000)
Offsetting assets, net asset balance	35,007	24,705
Offsetting assets, gross amounts not offset in balance sheet - financial instruments	(401)	(973)
Offsetting assets, gross amounts not offset in the balance sheet - collateral received	0	(8,029)
Offsetting assets, net amount	34,606	$ 15,703
Weighted average interest rate of reverse repurchase agreements, assets (percent)		3.20%
Repurchase agreements / reverse repurchase agreements, gross amounts of recognized liabilities		$ 50,000
Repurchase agreements / reverse repurchase agreements, gross amounts offset on balance sheet		(50,000)
Repurchase agreements / reverse repurchase agreements, net liability balance		0
Repurchase agreements / reverse repurchase agreements, gross amounts not offset in balance sheet - financial instruments		0
Repurchase agreements / reverse repurchase agreements, gross amounts not offset in balance sheet - collateral pledged		0
Repurchase agreements / reverse repurchase agreements, net amount		0
Derivatives, gross amounts of recognized liabilities	15,516	26,433
Derivatives, gross amounts offset on balance sheet	0	0
Derivatives, net liability balance	15,516	26,433
Derivatives, gross amounts not offset in balance sheet - financial instruments	(401)	(973)
Derivatives, gross amounts not offset in balance sheet - collateral pledged	(14,933)	(16,126)
Derivatives, net amount	182	9,334
Offsetting liabilities, gross amounts of recognized liabilities	15,516	76,433
Offsetting liabilities, gross amounts offset on balance sheet	0	(50,000)
Offsetting liabilities, net liability balance	15,516	26,433
Offsetting liabilities gross, amounts not offset in balance sheet - financial instruments	(401)	(973)
Offsetting liabilities gross amounts not offset in the balance sheet - collateral pledged	(14,933)	(16,126)
Offsetting liabilities, net amount	$ 182	$ 9,334
Weighted average interest rate of reverse repurchase agreements, liabilities (percent)		2.45%