Derivatives (Notional and Fair Values) (Details) MMBTU in Thousands, Boe in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020 USD ($) Boe MMBTU company	Dec. 31, 2019 USD ($) Boe MMBTU company
Derivative Asset [Abstract]
Derivative assets - Fair value	$ 708,610	$ 330,316
Less: Master netting agreements	(104,456)	(121,561)
Less: Cash collateral received/paid	(5,240)	(3,758)
Derivative asset, after netting	598,914	204,997
Derivative Liability [Abstract]
Derivative liabilities - Fair value	506,019	256,528
Less: Master netting agreements	(104,456)	(121,561)
Less: Cash collateral received/paid	(97,675)	(38,238)
Derivative liability, after netting	$ 303,888	$ 96,729
Crude oil \| Customer Counterparty
Derivative Liability [Abstract]
Derivative, nonmonetary notional amount, energy measure \| Boe	6,100	7,811
Natural gas \| Customer Counterparty
Derivative Liability [Abstract]
Derivative, nonmonetary notional amount, energy measure \| MMBTU	110,340	63,773
Derivative instruments designated as hedging instruments
Derivative Instruments
Notional amount	$ 371,186	$ 117,193
Derivative Asset [Abstract]
Derivative assets - Fair value	64	0
Derivative Liability [Abstract]
Derivative liabilities - Fair value	2,113	4,784
Derivative instruments designated as hedging instruments \| Fair Value Hedging \| Interest rate contracts
Derivative Instruments
Notional amount	15,194	31,026
Derivative Asset [Abstract]
Derivative assets - Fair value	64	0
Derivative Liability [Abstract]
Derivative liabilities - Fair value	0	3,198
Derivative instruments designated as hedging instruments \| Cash Flow Hedging \| Interest rate contracts
Derivative Instruments
Notional amount	275,000	0
Derivative Asset [Abstract]
Derivative assets - Fair value	0	0
Derivative Liability [Abstract]
Derivative liabilities - Fair value	1,861	0
Derivative instruments designated as hedging instruments \| Net Investment Hedging \| Foreign exchange contracts
Derivative Instruments
Notional amount	80,992	86,167
Derivative Asset [Abstract]
Derivative assets - Fair value	0	0
Derivative Liability [Abstract]
Derivative liabilities - Fair value	252	1,586
Derivatives not designated as hedging instruments
Derivative Instruments
Notional amount	19,523,762	20,540,031
Derivative Asset [Abstract]
Derivative assets - Fair value	708,546	330,316
Derivative Liability [Abstract]
Derivative liabilities - Fair value	503,906	251,744
Derivatives not designated as hedging instruments \| Interest rate contracts
Derivative Instruments
Notional amount	17,613,982	15,489,692
Derivative Asset [Abstract]
Derivative assets - Fair value	566,571	192,883
Derivative Liability [Abstract]
Derivative liabilities - Fair value	370,196	124,119
Derivatives not designated as hedging instruments \| Foreign exchange contracts
Derivative Instruments
Notional amount	1,832,383	4,839,661
Derivative Asset [Abstract]
Derivative assets - Fair value	19,134	54,637
Derivative Liability [Abstract]
Derivative liabilities - Fair value	14,530	47,024
Derivatives not designated as hedging instruments \| Credit contracts
Derivative Instruments
Notional amount	77,397	210,678
Derivative Asset [Abstract]
Derivative assets - Fair value	47	2
Derivative Liability [Abstract]
Derivative liabilities - Fair value	307	84
Derivatives not designated as hedging instruments \| Equity contracts
Derivative Instruments
Notional amount	0	0
Derivative Asset [Abstract]
Derivative assets - Fair value	12,765	1,414
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	110,029	81,380
Derivative Liability [Abstract]
Derivative liabilities - Fair value	$ 118,873	$ 80,517
Derivatives not designated as hedging instruments \| Equity, Public Companies
Derivative Liability [Abstract]
Number of companies that issued the equity (issuers portion only) \| company	3	3
Derivatives not designated as hedging instruments \| Equity, Private Companies
Derivative Liability [Abstract]
Number of companies that issued the equity (issuers portion only) \| company	17	18

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