Derivatives, Fair Value of Derivatives Contracts (Details) - USD ($) $ in Thousands	Dec. 31, 2016		Dec. 31, 2015
Derivative Assets, Fair Value, Net [Abstract]
Derivative contracts, net of cash margin, Assets, Fair Value	$ 689,872		$ 586,270
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	664,531		581,701
Not Designated as Hedging Instrument [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	22,437,314	[1]	17,153,221	[2]
Derivative Liabilities, Notional	22,178,359	[1]	16,785,014	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	789,791		663,343
Derivative Assets, Netting Adjustments	(89,368)		(52,433)
Derivative Assets, Net Fair Value Before Cash Collateral	700,423		610,910
Derivative Assets, Fair Value, Cash Collateral	(10,551)		(24,640)
Derivative contracts, net of cash margin, Assets, Fair Value	689,872		586,270
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Fair Value, Gross Liability	801,809		659,171
Derivative Liabilities, Netting Adjustments	(89,368)		(52,433)
Derivative Liabilities, Net Fair Value Before Cash Collateral	712,441		606,738
Derivative Liabilities, Fair Value, Cash Collateral	(47,910)		(25,037)
Derivative contracts, net of cash margin, Liabilities, Fair Value	664,531		581,701
Not Designated as Hedging Instrument [Member] | To-be-announced residential mortgage-backed securities [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	16,949,152	[1]	14,583,052	[2]
Derivative Liabilities, Notional	16,637,532	[1]	14,168,927	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	180,695		43,270
Derivative Assets, Netting Adjustments	(60,555)		(28,305)
Derivative Assets, Net Fair Value Before Cash Collateral	120,140		14,965
Derivative Assets, Fair Value, Cash Collateral	0		0
Derivative contracts, net of cash margin, Assets, Fair Value	120,140		14,965
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Fair Value, Gross Liability	176,928		40,141
Derivative Liabilities, Netting Adjustments	(60,555)		(28,305)
Derivative Liabilities, Net Fair Value Before Cash Collateral	116,373		11,836
Derivative Liabilities, Fair Value, Cash Collateral	0		(1,308)
Derivative contracts, net of cash margin, Liabilities, Fair Value	116,373		10,528
Not Designated as Hedging Instrument [Member] | Interest rate swaps [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	1,403,408	[1]	1,332,044	[2]
Derivative Liabilities, Notional	1,403,408	[1]	1,332,044	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	34,442		31,744
Derivative Assets, Netting Adjustments	0		0
Derivative Assets, Net Fair Value Before Cash Collateral	34,442		31,744
Derivative Assets, Fair Value, Cash Collateral	(4,567)		(1,424)
Derivative contracts, net of cash margin, Assets, Fair Value	29,875		30,320
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Fair Value, Gross Liability	34,442		31,928
Derivative Liabilities, Netting Adjustments	0		0
Derivative Liabilities, Net Fair Value Before Cash Collateral	34,442		31,928
Derivative Liabilities, Fair Value, Cash Collateral	(11,977)		(20,530)
Derivative contracts, net of cash margin, Liabilities, Fair Value	22,465		11,398
Not Designated as Hedging Instrument [Member] | Energy contracts [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	835,566	[1]	470,613	[2]
Derivative Liabilities, Notional	820,365	[1]	463,703	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	64,140		83,045
Derivative Assets, Netting Adjustments	(28,298)		(22,970)
Derivative Assets, Net Fair Value Before Cash Collateral	35,842		60,075
Derivative Assets, Fair Value, Cash Collateral	(71)		(18,606)
Derivative contracts, net of cash margin, Assets, Fair Value	35,771		41,469
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Fair Value, Gross Liability	64,306		81,869
Derivative Liabilities, Netting Adjustments	(28,298)		(22,970)
Derivative Liabilities, Net Fair Value Before Cash Collateral	36,008		58,899
Derivative Liabilities, Fair Value, Cash Collateral	(31,534)		0
Derivative contracts, net of cash margin, Liabilities, Fair Value	4,474		58,899
Not Designated as Hedging Instrument [Member] | Agricultural contracts [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	53,209	[1]	61,662	[2]
Derivative Liabilities, Notional	53,216	[1]	61,657	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	1,382		2,591
Derivative Assets, Netting Adjustments	(515)		(1,158)
Derivative Assets, Net Fair Value Before Cash Collateral	867		1,433
Derivative Assets, Fair Value, Cash Collateral	0		0
Derivative contracts, net of cash margin, Assets, Fair Value	867		1,433
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Fair Value, Gross Liability	1,365		2,579
Derivative Liabilities, Netting Adjustments	(515)		(1,158)
Derivative Liabilities, Net Fair Value Before Cash Collateral	850		1,421
Derivative Liabilities, Fair Value, Cash Collateral	(769)		(1,248)
Derivative contracts, net of cash margin, Liabilities, Fair Value	81		173
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	580,886	[1]	546,572	[2]
Derivative Liabilities, Notional	580,712	[1]	546,405	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	494,349		498,830
Derivative Assets, Netting Adjustments	0		0
Derivative Assets, Net Fair Value Before Cash Collateral	494,349		498,830
Derivative Assets, Fair Value, Cash Collateral	(5,183)		(4,140)
Derivative contracts, net of cash margin, Assets, Fair Value	489,166		494,690
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Fair Value, Gross Liability	494,695		498,574
Derivative Liabilities, Netting Adjustments	0		0
Derivative Liabilities, Net Fair Value Before Cash Collateral	494,695		498,574
Derivative Liabilities, Fair Value, Cash Collateral	(3,630)		(1,951)
Derivative contracts, net of cash margin, Liabilities, Fair Value	491,065		496,623
Not Designated as Hedging Instrument [Member] | Equity option contracts [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	100,924	[1]	137,278	[2]
Derivative Liabilities, Notional	100,924	[1]	137,278	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	4,357		3,780
Derivative Assets, Netting Adjustments	0		0
Derivative Assets, Net Fair Value Before Cash Collateral	4,357		3,780
Derivative Assets, Fair Value, Cash Collateral	(730)		(470)
Derivative contracts, net of cash margin, Assets, Fair Value	3,627		3,310
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Fair Value, Gross Liability	4,357		3,780
Derivative Liabilities, Netting Adjustments	0		0
Derivative Liabilities, Net Fair Value Before Cash Collateral	4,357		3,780
Derivative Liabilities, Fair Value, Cash Collateral	0		0
Derivative contracts, net of cash margin, Liabilities, Fair Value	4,357		3,780
Not Designated as Hedging Instrument [Member] | Customer risk management programs [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	19,923,145	[1]	17,131,221	[2]
Derivative Liabilities, Notional	19,596,157	[1]	16,710,014	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	779,365		663,260
Derivative Assets, Netting Adjustments	(89,368)		(52,433)
Derivative Assets, Net Fair Value Before Cash Collateral	689,997		610,827
Derivative Assets, Fair Value, Cash Collateral	(10,551)		(24,640)
Derivative contracts, net of cash margin, Assets, Fair Value	679,446		586,187
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Fair Value, Gross Liability	776,093		658,871
Derivative Liabilities, Netting Adjustments	(89,368)		(52,433)
Derivative Liabilities, Net Fair Value Before Cash Collateral	686,725		606,438
Derivative Liabilities, Fair Value, Cash Collateral	(47,910)		(25,037)
Derivative contracts, net of cash margin, Liabilities, Fair Value	638,815		581,401
Not Designated as Hedging Instrument [Member] | Internal risk management programs [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	2,514,169	[1]	22,000	[2]
Derivative Liabilities, Notional	2,582,202	[1]	75,000	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	10,426		83
Derivative Assets, Netting Adjustments	0		0
Derivative Assets, Net Fair Value Before Cash Collateral	10,426		83
Derivative Assets, Fair Value, Cash Collateral	0		0
Derivative contracts, net of cash margin, Assets, Fair Value	10,426		83
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Fair Value, Gross Liability	25,716		300
Derivative Liabilities, Netting Adjustments	0		0
Derivative Liabilities, Net Fair Value Before Cash Collateral	25,716		300
Derivative Liabilities, Fair Value, Cash Collateral	0		0
Derivative contracts, net of cash margin, Liabilities, Fair Value	$ 25,716		$ 300

[1] Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.

[2] Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.