Derivatives (Notional and Fair Values) (Details) MMBTU in Thousands, Boe in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021 USD ($) MMBTU Boe company	Dec. 31, 2020 USD ($) Boe MMBTU company
Derivative Asset [Abstract]
Derivative assets - Fair value	$ 457,317	$ 602,754
Less: Master netting agreements	(100,454)	(93,063)
Less: Cash collateral received/paid	(7,781)	(8,449)
Net derivative assets	349,082	501,242
Derivative Liability [Abstract]
Derivative liabilities - Fair value	344,135	424,828
Less: Master netting agreements	(100,454)	(93,063)
Less: Cash collateral received/paid	(86,233)	(91,634)
Net derivative liabilities	$ 157,448	$ 240,131
Crude oil \| Customer Counterparty
Derivative Liability [Abstract]
Derivative, nonmonetary notional amount, energy measure \| Boe	8,258	6,321
Natural gas \| Customer Counterparty
Derivative Liability [Abstract]
Derivative, nonmonetary notional amount, energy measure \| MMBTU	102,996	109,635
Derivative instruments designated as hedging instruments
Derivative Instruments
Notional Amount	$ 358,936	$ 359,269
Derivative Asset [Abstract]
Derivative assets - Fair value	908	0
Derivative Liability [Abstract]
Derivative liabilities - Fair value	1,258	2,099
Derivative instruments designated as hedging instruments \| Cash Flow Hedging \| Interest rate contracts
Derivative Instruments
Notional Amount	275,000	275,000
Derivative Asset [Abstract]
Derivative assets - Fair value	0	0
Derivative Liability [Abstract]
Derivative liabilities - Fair value	1,258	1,864
Derivative instruments designated as hedging instruments \| Net Investment Hedging \| Foreign exchange contracts
Derivative Instruments
Notional Amount	83,936	84,269
Derivative Asset [Abstract]
Derivative assets - Fair value	908	0
Derivative Liability [Abstract]
Derivative liabilities - Fair value	0	235
Derivatives not designated as hedging instruments
Derivative Instruments
Notional Amount	22,005,910	21,341,158
Derivative Asset [Abstract]
Derivative assets - Fair value	456,409	602,754
Derivative Liability [Abstract]
Derivative liabilities - Fair value	342,877	422,729
Derivatives not designated as hedging instruments \| Interest rate contracts
Derivative Instruments
Notional Amount	17,891,960	18,155,678
Derivative Asset [Abstract]
Derivative assets - Fair value	319,049	489,132
Derivative Liability [Abstract]
Derivative liabilities - Fair value	229,032	315,834
Derivatives not designated as hedging instruments \| Foreign exchange contracts
Derivative Instruments
Notional Amount	4,036,958	3,108,488
Derivative Asset [Abstract]
Derivative assets - Fair value	38,654	30,300
Derivative Liability [Abstract]
Derivative liabilities - Fair value	27,287	22,524
Derivatives not designated as hedging instruments \| Credit contracts
Derivative Instruments
Notional Amount	76,992	76,992
Derivative Asset [Abstract]
Derivative assets - Fair value	5	13
Derivative Liability [Abstract]
Derivative liabilities - Fair value	153	206
Derivatives not designated as hedging instruments \| Equity contracts
Derivative Instruments
Notional Amount	0	0
Derivative Asset [Abstract]
Derivative assets - Fair value	272	858
Derivative Liability [Abstract]
Derivative liabilities - Fair value	0	0
Derivatives not designated as hedging instruments \| Commodity contracts
Derivative Instruments
Notional Amount	0	0
Derivative Asset [Abstract]
Derivative assets - Fair value	98,429	82,451
Derivative Liability [Abstract]
Derivative liabilities - Fair value	$ 86,405	$ 84,165
Derivatives not designated as hedging instruments \| Equity, Public Companies
Derivative Liability [Abstract]
Number of companies that issued the equity (issuers portion only) \| company		2
Derivatives not designated as hedging instruments \| Equity, Private Companies
Derivative Liability [Abstract]
Number of companies that issued the equity (issuers portion only) \| company	18	17

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