Fair Value Recurring Changes in Fair Value (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Trading securities	$ 16,306		$ 17,950
Available-for-sale securities	0
Mortgage loans held for investment	0
Other assets [Abstract]
Derivatives	0
Total assets at fair value	52,939		93,736
Other liabilities [Abstract]
Derivatives	0
Total liabilities at fair value	0
Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Trading securities	11,688		20,459
Available-for-sale securities	19,159		38,147
Mortgage loans held for investment	2,599,667		2,567,022
Other assets [Abstract]
Derivatives	10,430		16,051
Total assets at fair value	2,694,859		2,694,632
Other liabilities [Abstract]
Derivatives	10,734		22,590
Total liabilities at fair value	3,231,253		3,347,367
Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Trading securities	2,774		2,286
Available-for-sale securities	19,012		25,034
Mortgage loans held for investment	392,355		466,594
Other assets [Abstract]
Derivatives	65		175
Total assets at fair value	415,630		495,561
Other liabilities [Abstract]
Derivatives	105		161
Total liabilities at fair value	19,611		23,984
Netting Adjustment [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Mortgage loans held for investment	0		0
Other assets [Abstract]
Derivatives	(8,422)		(15,791)
Total assets at fair value	(8,422)		(15,791)
Other liabilities [Abstract]
Derivatives	(9,370)		(22,046)
Total liabilities at fair value	(9,370)		(22,046)
Estimated Fair Value [Member]
Assets [Abstract]
Trading securities	30,768		40,695
Available-for-sale securities	38,171		63,181
Mortgage loans held for investment	2,992,022		3,033,616
Other assets [Abstract]
Derivatives	2,073		435
Total assets at fair value	3,155,006		3,268,138
Other liabilities [Abstract]
Derivatives	1,469		705
Total liabilities at fair value	3,241,494		3,349,305
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Cash equivalents			1,150	[1]
Trading securities	16,306		17,950
Available-for-sale securities	0		0
Other assets [Abstract]
Derivatives	0		0
Total assets at fair value	16,306		19,100
Liabilities [Abstract]
Long-term debt	0		0
Other liabilities [Abstract]
Derivatives	0		0
Total liabilities at fair value	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage commitment derivatives [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury Securities [Member]
Assets [Abstract]
Trading securities	16,306		17,950
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Cash equivalents			0	[1]
Trading securities	11,688		20,459
Available-for-sale securities	19,159		38,147
Other assets [Abstract]
Derivatives	10,430		16,051
Total assets at fair value	52,841		82,823
Liabilities [Abstract]
Long-term debt	14,811		10,912
Other liabilities [Abstract]
Derivatives	10,734		22,590
Total liabilities at fair value	25,545		33,502
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives	9,604		12,224
Other liabilities [Abstract]
Derivatives	9,444		19,836
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives	561		3,674
Other liabilities [Abstract]
Derivatives	1,084		2,463
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		1
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage commitment derivatives [Member]
Other assets [Abstract]
Derivatives	265		153
Other liabilities [Abstract]
Derivatives	206		290
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	5,828		6,180
Available-for-sale securities	6,566		10,406
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	1,837		2,791
Available-for-sale securities	6,834		9,370
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	407		436
Available-for-sale securities	588		751
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	898		1,226
Available-for-sale securities	3,558		4,511
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	2,718		9,826
Available-for-sale securities	1,606		13,097
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	3		5
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	4		7
Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury Securities [Member]
Assets [Abstract]
Trading securities	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Cash equivalents			0	[1]
Trading securities	2,774		2,286
Available-for-sale securities	19,012		25,034
Other assets [Abstract]
Derivatives	65		175
Total assets at fair value	24,555		30,129
Liabilities [Abstract]
Long-term debt	1,473		1,528
Other liabilities [Abstract]
Derivatives	105		161
Total liabilities at fair value	1,578		1,689
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives	36		146
Other liabilities [Abstract]
Derivatives	96		154
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives	1		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other [Member]
Other assets [Abstract]
Derivatives	28		26
Other liabilities [Abstract]
Derivatives	1		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage commitment derivatives [Member]
Other assets [Abstract]
Derivatives	0		3
Other liabilities [Abstract]
Derivatives	8		7
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	42		68
Available-for-sale securities	7		29
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	2		2
Available-for-sale securities	8		10
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	0		1
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	618		104
Available-for-sale securities	3,791		6,564
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	1,448		1,319
Available-for-sale securities	7,068		7,447
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	565		675
Available-for-sale securities	5,253		7,837
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other [Member]
Assets [Abstract]
Trading securities	99		117
Available-for-sale securities	2,885		3,147
Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury Securities [Member]
Assets [Abstract]
Trading securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member]
Assets [Abstract]
Cash equivalents			0	[1]
Trading securities	0		0
Available-for-sale securities	0		0
Other assets [Abstract]
Derivatives	(8,422)	[2]	(15,791)	[2]
Total assets at fair value	(8,422)	[2]	(15,791)	[2]
Liabilities [Abstract]
Long-term debt	0		0
Other liabilities [Abstract]
Derivatives	(9,370)	[2]	(22,046)	[2]
Total liabilities at fair value	(9,370)	[2]	(22,046)	[2]
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Other [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives	(8,422)	[2]	(15,791)	[2]
Other liabilities [Abstract]
Derivatives	(9,370)	[2]	(22,046)	[2]
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Mortgage commitment derivatives [Member]
Other assets [Abstract]
Derivatives	0		0
Other liabilities [Abstract]
Derivatives	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Other [Member]
Assets [Abstract]
Trading securities	0		0
Available-for-sale securities	0		0
Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | U.S. Treasury Securities [Member]
Assets [Abstract]
Trading securities	0		0
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member]
Assets [Abstract]
Cash equivalents			1,150	[1]
Trading securities	30,768		40,695
Available-for-sale securities	38,171		63,181
Other assets [Abstract]
Derivatives	2,073		435
Total assets at fair value	85,280		116,261
Liabilities [Abstract]
Long-term debt	16,284		12,440
Other liabilities [Abstract]
Derivatives	1,469		705
Total liabilities at fair value	17,753		13,145
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Swaps [Member]
Other assets [Abstract]
Derivatives	9,640		12,370
Other liabilities [Abstract]
Derivatives	9,540		19,990
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Swaptions [Member]
Other assets [Abstract]
Derivatives	562		3,674
Other liabilities [Abstract]
Derivatives	1,084		2,463
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Other [Member]
Other assets [Abstract]
Derivatives	28		26
Other liabilities [Abstract]
Derivatives	1		1
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Netting adjustment [Member]
Other assets [Abstract]
Derivatives	(8,422)		(15,791)
Other liabilities [Abstract]
Derivatives	(9,370)		(22,046)
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Mortgage commitment derivatives [Member]
Other assets [Abstract]
Derivatives	265		156
Other liabilities [Abstract]
Derivatives	214		297
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Fannie Mae [Member]
Assets [Abstract]
Trading securities	5,870		6,248
Available-for-sale securities	6,573		10,435
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Freddie Mac [Member]
Assets [Abstract]
Trading securities	1,839		2,793
Available-for-sale securities	6,842		9,380
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Ginnie Mae [Member]
Assets [Abstract]
Trading securities	407		437
Available-for-sale securities	588		751
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Alt-A private-label securities [Member]
Assets [Abstract]
Trading securities	1,516		1,330
Available-for-sale securities	7,349		11,075
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Subprime private-label securities [Member]
Assets [Abstract]
Trading securities	1,448		1,319
Available-for-sale securities	7,068		7,447
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | CMBS [Member]
Assets [Abstract]
Trading securities	2,718		9,826
Available-for-sale securities	1,606		13,097
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Mortgage revenue bonds [Member]
Assets [Abstract]
Trading securities	565		675
Available-for-sale securities	5,256		7,842
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Other [Member]
Assets [Abstract]
Trading securities	99		117
Available-for-sale securities	2,889		3,154
Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | U.S. Treasury Securities [Member]
Assets [Abstract]
Trading securities	16,306		17,950
Fannie Mae [Member]
Liabilities [Abstract]
Long-term debt	1,308		793
Fannie Mae [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Mortgage loans held for investment	0
Liabilities [Abstract]
Long-term debt	0
Fannie Mae [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Mortgage loans held for investment	29,920		39,018
Liabilities [Abstract]
Long-term debt	463,991		534,516
Fannie Mae [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Mortgage loans held for investment	215,960		232,170
Liabilities [Abstract]
Long-term debt	1,557		1,056
Fannie Mae [Member] | Netting Adjustment [Member]
Assets [Abstract]
Mortgage loans held for investment	0		0
Liabilities [Abstract]
Long-term debt	0		0
Fannie Mae [Member] | Estimated Fair Value [Member]
Assets [Abstract]
Mortgage loans held for investment	245,880		271,188
Liabilities [Abstract]
Long-term debt	465,548		535,572
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Liabilities [Abstract]
Long-term debt	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Liabilities [Abstract]
Long-term debt	353		393
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt	353		393
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member]
Liabilities [Abstract]
Long-term debt	955		400
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt	955		400
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Netting Adjustment [Member]
Liabilities [Abstract]
Long-term debt	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Netting Adjustment [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt	0		0
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member]
Liabilities [Abstract]
Long-term debt	1,308		793
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Senior Fixed [Member]
Liabilities [Abstract]
Long-term debt	353		393
Fannie Mae [Member] | Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member] | Senior Floating [Member]
Liabilities [Abstract]
Long-term debt	955		400
Consolidated Trusts [Member]
Assets [Abstract]
Mortgage loans held for investment	14,268		10,800
Liabilities [Abstract]
Long-term debt	14,976		11,647
Consolidated Trusts [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Mortgage loans held for investment	0
Liabilities [Abstract]
Long-term debt	0
Consolidated Trusts [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Mortgage loans held for investment	2,569,747		2,528,004
Liabilities [Abstract]
Long-term debt	2,684,224		2,685,008
Consolidated Trusts [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Mortgage loans held for investment	176,395		234,424
Liabilities [Abstract]
Long-term debt	13,362		16,171
Consolidated Trusts [Member] | Netting Adjustment [Member]
Assets [Abstract]
Mortgage loans held for investment	0		0
Liabilities [Abstract]
Long-term debt	0		0
Consolidated Trusts [Member] | Estimated Fair Value [Member]
Assets [Abstract]
Mortgage loans held for investment	2,746,142		2,762,428
Liabilities [Abstract]
Long-term debt	2,697,586		2,701,179
Consolidated Trusts [Member] | Recurring Fair Value Measurements [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Mortgage loans held for investment	0		0
Liabilities [Abstract]
Long-term debt	0		0
Consolidated Trusts [Member] | Recurring Fair Value Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Mortgage loans held for investment	11,564		8,166
Liabilities [Abstract]
Long-term debt	14,458		10,519
Consolidated Trusts [Member] | Recurring Fair Value Measurements [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Mortgage loans held for investment	2,704		2,634
Liabilities [Abstract]
Long-term debt	518		1,128
Consolidated Trusts [Member] | Recurring Fair Value Measurements [Member] | Netting Adjustment [Member]
Assets [Abstract]
Mortgage loans held for investment	0		0
Liabilities [Abstract]
Long-term debt	0		0
Consolidated Trusts [Member] | Recurring Fair Value Measurements [Member] | Estimated Fair Value [Member]
Assets [Abstract]
Mortgage loans held for investment	14,268		10,800
Liabilities [Abstract]
Long-term debt	$ 14,976		$ 11,647

[1] Cash equivalents are comprised of U.S. Treasuries that are classified as Level 1.

[2] Derivative contracts are reported on a gross basis by level. The netting adjustment represents the effect of the legal right to offset under legally enforceable master netting agreements to settle with the same counterparty on a net basis, including cash collateral posted and received.