Loans Receivable (Schedule of Consumer Loans Forecasted Collection Percentage) (Details)		Sep. 30, 2019		Jun. 30, 2019	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Loans Originating In 2010 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Collection Percentage		77.70%	[1]	77.70%	77.70%	[1]
Initial Forecasted Collection Percentage	[1]													73.60%
Variance In Forecasted Collection Percentage From Prior Quarter End		0.00%
Variance In Forecasted Collection Percentage From Prior Year End		0.00%
Variance In Initial Forecasted Collection Percentage		4.10%
Loans Originating In 2011 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Collection Percentage		74.80%	[1]	74.80%	74.70%	[1]
Initial Forecasted Collection Percentage	[1]												72.50%
Variance In Forecasted Collection Percentage From Prior Quarter End		0.00%
Variance In Forecasted Collection Percentage From Prior Year End		0.10%
Variance In Initial Forecasted Collection Percentage		2.30%
Loans Originating In 2012 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Collection Percentage		73.90%	[1]	73.90%	73.80%	[1]
Initial Forecasted Collection Percentage	[1]											71.40%
Variance In Forecasted Collection Percentage From Prior Quarter End		0.00%
Variance In Forecasted Collection Percentage From Prior Year End		0.10%
Variance In Initial Forecasted Collection Percentage		2.50%
Loans Originating In 2013 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Collection Percentage		73.50%	[1]	73.50%	73.50%	[1]
Initial Forecasted Collection Percentage	[1]										72.00%
Variance In Forecasted Collection Percentage From Prior Quarter End		0.00%
Variance In Forecasted Collection Percentage From Prior Year End		0.00%
Variance In Initial Forecasted Collection Percentage		1.50%
Loans Originating In 2014 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Collection Percentage		71.80%	[1]	71.80%	71.70%	[1]
Initial Forecasted Collection Percentage	[1]									71.80%
Variance In Forecasted Collection Percentage From Prior Quarter End		0.00%
Variance In Forecasted Collection Percentage From Prior Year End		0.10%
Variance In Initial Forecasted Collection Percentage		0.00%
Loans Originating In 2015 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Collection Percentage		65.50%	[1]	65.50%	65.40%	[1]
Initial Forecasted Collection Percentage	[1]								67.70%
Variance In Forecasted Collection Percentage From Prior Quarter End		0.00%
Variance In Forecasted Collection Percentage From Prior Year End		0.10%
Variance In Initial Forecasted Collection Percentage		(2.20%)
Loans Originating In 2016 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Collection Percentage		64.10%	[1]	64.20%	64.20%	[1]
Initial Forecasted Collection Percentage	[1]							65.40%
Variance In Forecasted Collection Percentage From Prior Quarter End		(0.10%)
Variance In Forecasted Collection Percentage From Prior Year End		(0.10%)
Variance In Initial Forecasted Collection Percentage		(1.30%)
Loans Originating In 2017 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Collection Percentage		65.00%	[1]	65.10%	65.50%	[1]
Initial Forecasted Collection Percentage	[1]						64.00%
Variance In Forecasted Collection Percentage From Prior Quarter End		(0.10%)
Variance In Forecasted Collection Percentage From Prior Year End		(0.50%)
Variance In Initial Forecasted Collection Percentage		1.00%
Loans Originating In 2018 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Collection Percentage		65.40%	[1]	65.50%	65.00%	[1]
Initial Forecasted Collection Percentage	[1]				63.60%
Variance In Forecasted Collection Percentage From Prior Quarter End		(0.10%)
Variance In Forecasted Collection Percentage From Prior Year End		0.40%
Variance In Initial Forecasted Collection Percentage		1.80%
Loans Originating In 2019 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Collection Percentage		64.80%	[1]	64.70%
Initial Forecasted Collection Percentage	[1]	64.10%
Variance In Forecasted Collection Percentage From Prior Quarter End		0.10%
Variance In Initial Forecasted Collection Percentage		0.70%

[1] Represents the total forecasted collections we expect to collect on the Consumer Loans as a percentage of the repayments that we were contractually owed on the Consumer Loans at the time of assignment. Contractual repayments include both principal and interest. Forecasted collection rates are negatively impacted by canceled Consumer Loans as the contractual amount owed is not removed from the denominator for purposes of computing forecasted collection rates in the table. (2) The forecasted collection rate for 2019 Consumer Loans as of September 30, 2019 includes both Consumer Loans that were in our portfolio as of June 30, 2019 and Consumer Loans assigned during the most recent quarter. The following table provides forecasted collection rates for each of these segments:     Forecasted Collection Percentage as of   Current Forecast Variance from 2019 Consumer Loan Assignment Period   September 30, 2019   June 30, 2019   Initial Forecast   June 30, 2019   Initial Forecast January 1, 2019 through June 30, 2019   65.1 %   64.7 %   64.2 %   0.4 %   0.9 % July 1, 2019 through September 30, 2019   64.1 %   —
  64.0 %   —
  0.1 %