Fair Value Measurements (Narrative) (Details) - Recurring [Member]	Jun. 30, 2019 USD ($) shares
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Transfers of assets and liabilities between levels | $	$ 0
Visa Inc [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Number of shares of Visa Class B common stock | shares	192,163
Investment Securities [Member] | Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Targeted duration	2 years
Investment Securities [Member] | Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Targeted duration	5 years 6 months