Fair Value Measurements - Table of Valuation Techniques and Unobservable Inputs Used in Valuation of Financial Instruments Falling Within Level 3 of Fair Value Hierarchy (Details)	Mar. 31, 2019 item
Minimum | Impaired loans [Member] | Measurement Input, Discount Rate [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value of loans measurement input (as a percent)	0.00
Minimum | Mortgage servicing rights member | Measurement Input, Discount Rate [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Servicing assets measurement input (as a percent)	0.095
Minimum | Mortgage servicing rights member | Measurement Input, Constant Prepayment Rate [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Servicing assets measurement input (as a percent)	13.4
Maximum | Impaired loans [Member] | Measurement Input, Discount Rate [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value of loans measurement input (as a percent)	0.25
Maximum | Mortgage servicing rights member | Measurement Input, Discount Rate [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Servicing assets measurement input (as a percent)	0.105
Maximum | Mortgage servicing rights member | Measurement Input, Constant Prepayment Rate [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Servicing assets measurement input (as a percent)	19.8