Summary of Significant Accounting Policies - Summary of Significant Accounting Policies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Interest rate swap | Derivatives designated as hedges
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative liability, notional amount	$ 150.0
Forward foreign exchange contracts | Net investment hedges
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Maximum remaining maturity of foreign currency derivatives	34 days
Forward foreign exchange contracts | Not Designated as Hedges
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Maximum remaining maturity of foreign currency derivatives	34 days
Minimum
Non-accrual Loans and Leases
Number of days interest and principal are past due for loans and leases to be placed on non-accrual status	90 days
Number of days interest and principal for third party consumer first mortgage lien are past due to be placed on non-accrual status	90 days
Sustained repayment performance period through which loans and leases are reported as non-accrual loans and leases	6 months
Sustained repayment performance period through which income on loans and leases is recognized on cash basis	9 months
Minimum | Interest rate contracts | Not Designated as Hedges
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative, term of contract	3 years
Maximum
Allowance for Loan and Lease Losses
Number of days past due to be considered to charge off consumer real estate loans	150 days
Number of days past due to be considered to charge off auto finance loans in full	120 days
Number of days from date of overdraft to report net losses on uncollectible overdrafts as net charge-offs in allowance for loan and lease losses	60 days
Number of days past due to be considered to charge off uncollectible overdrafts	60 days
Non-accrual Loans and Leases
Sustained repayment performance period through which income on loans and leases is recognized on cash basis	12 months
Number of days delinquent through which income on loans and leases is recognized on cash basis	60 days
Maximum | Interest rate contracts | Not Designated as Hedges
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative, term of contract	11 years
Maximum | Interest rate lock commitments | Not Designated as Hedges
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative, remaining maturity	3 months