Fair Value - Quantitative Information about Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Non Recurring Basis (Details) - Fair Value, Measurements, Nonrecurring - Significant Unobservable Inputs $ in Thousands	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Commercial, industrial and agricultural
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	$ 5,627	$ 2,910
Commercial mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	$ 10,909	$ 1,147
Measurement Input, Loss Severity | Commercial, industrial and agricultural | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0	0
Measurement Input, Loss Severity | Commercial, industrial and agricultural | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	1	0.6
Measurement Input, Loss Severity | Commercial, industrial and agricultural | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.22	0.54
Measurement Input, Loss Severity | Commercial mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.25
Measurement Input, Loss Severity | Commercial mortgages | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input		0.25
Measurement Input, Loss Severity | Commercial mortgages | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	1	0.01
Measurement Input, Loss Severity | Commercial mortgages | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.30	0.52