Summary of Significant Accounting Policies (Equipment, Office Facilities, and Property) (Details)	12 Months Ended
	Dec. 31, 2020
All equipment types and furniture [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life, property, plant and equipment	3 years
All equipment types and furniture [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life, property, plant and equipment	10 years
Buildings [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life, property, plant and equipment	40 years
Building improvements and land improvements [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life, property, plant and equipment	20 years
Software [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life, Software and certain costs incurred for purchasing or developing software, less than	3 years
Software [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life, property, plant and equipment	3 years
Software [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life, property, plant and equipment	10 years