Summary Of Significant Accounting Policies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Loan impairment threshold period	90 days
Threshold of reporting unit goodwill carrying value for further analysis	$ 0
Goodwill impairment charges	0
Allowance for doubtful accounts	18,700,000	$ 14,300,000
Incremental payments due upon termination of contract	0
Right-of-use assets	793,200,000	725,800,000
Lease liabilities	839,806,000	$ 766,000,000.0
ASU 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Increase in allowance for credit losses	10,400,000
ASU 2016-13 [Member] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative adjustments for accounting changes	7,800,000
Cumulative adjustments for accounting changes	7,800,000
ASU 2017-08 [Member] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative adjustments for accounting changes			$ 4,400,000
Cumulative adjustments for accounting changes			4,400,000
ASU 2016-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Right-of-use assets			$ 670,000,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]			us-gaap:PropertyPlantAndEquipmentNet
Lease liabilities			$ 670,000,000
Operating Lease, Liability, Statement of Financial Position [Extensible List]			us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
ASU 2016-02 [Member] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative adjustments for accounting changes			$ 6,700,000
Cumulative adjustments for accounting changes			$ 6,700,000
ASU 2018-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification adjustment related to cash flow hedges and investment portfolio credit risk	$ 3,100,000
Office Equipment [Member] | Minimum [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Fixed assets, Useful life	2 years
Office Equipment [Member] | Maximum [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Fixed assets, Useful life	7 years
Building and Building Improvements [Member] | Minimum [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Fixed assets, Useful life	3 years
Building and Building Improvements [Member] | Maximum [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Fixed assets, Useful life	39 years
Aircraft Engines Held for Operating Lease [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Fixed assets, Useful life	30 years
Fixed assets, residual value percentage	15.00%