Loans - Loans by FICO Score, Consumer (Details) - Consumer	Sep. 30, 2019	Dec. 31, 2018
HELOC | FICO score 740 or greater
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	61.90%	61.40%
HELOC | FICO score 720-739
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	8.80%	8.50%
HELOC | FICO score 700-719
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	7.30%	7.60%
HELOC | FICO score 660-699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	10.50%	10.90%
HELOC | FICO score 620-659
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	5.10%	5.10%
HELOC | FICO score less than 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	6.40%	6.50%
HELOC | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	100.00%	100.00%
R/E Installment Loans | FICO score 740 or greater
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	72.90%	71.30%
R/E Installment Loans | FICO score 720-739
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	8.10%	8.80%
R/E Installment Loans | FICO score 700-719
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	6.20%	7.00%
R/E Installment Loans | FICO score 660-699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	7.40%	7.60%
R/E Installment Loans | FICO score 620-659
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	2.90%	2.80%
R/E Installment Loans | FICO score less than 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	2.50%	2.50%
R/E Installment Loans | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	100.00%	100.00%
Permanent mortgage | FICO score 740 or greater
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	47.90%	51.80%
Permanent mortgage | FICO score 720-739
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	7.90%	7.60%
Permanent mortgage | FICO score 700-719
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	11.00%	10.60%
Permanent mortgage | FICO score 660-699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	16.70%	14.70%
Permanent mortgage | FICO score 620-659
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	8.20%	6.50%
Permanent mortgage | FICO score less than 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	8.30%	8.80%
Permanent mortgage | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average refreshed FICO score (percent)	100.00%	100.00%