Summary Of Significant Accounting Policies (Details) - USD ($)		12 Months Ended
	Oct. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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
Incremental payments due upon termination of contract		$ 0
Corporate tax rate		21.00%	35.00%
Other operating expenses		$ 315,152,000	$ 297,634,000	$ 291,615,000
Shares withheld from employee awards for tax withholding purposes		43,229,000	214,744,000	61,601,000
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
ASU 2016-18 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Increase in net cash provided by operating activities			$ 17,600,000	153,800,000
ASU 2014-09 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect on retained earnings		4,200,000
Capital raising and advisory fee revenues		33,800,000
Other operating expenses		33,800,000
Reclassification from Operating Activities to Financing Activities [Member] | ASU No. 2016-09 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Shares withheld from employee awards for tax withholding purposes				$ 61,600,000
Minimum [Member] | ASU 2016-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease, right-of-use asset		600,000,000
Maximum [Member] | ASU 2016-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease, right-of-use asset		$ 700,000,000
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