Subsidiary Information - Condensed Consolidating Statement of Operations (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues
Net earned premiums	[1]	$ 214	$ 219	$ 397	$ 361
Net investment income		98	98	197	199
Net realized investment gains (losses)		10	(9)	(3)	7
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements		24	8	32	29
Net unrealized gains (losses)		39	82	(29)	185
Net change in fair value of credit derivatives		63	90	3	214
Bargain purchase gain and settlement of pre-existing relationships		0	214	0	214
Other		11	83	47	69
Total revenues		396	695	641	1,064
Expenses
Loss and LAE		102	188	192	206
Amortization of DAC		5	6	9	10
Interest expense		25	26	51	51
Other operating expenses		63	66	123	122
Total expenses		195	286	375	389
Income (loss) before income taxes		201	409	266	675
Total (provision) benefit for income taxes		(55)	(112)	(61)	(177)
Equity in net earnings of subsidiaries		0	0	0	0
Net income (loss)		146	297	205	498
Less: noncontrolling interest		0	0	0	0
Net income (loss)		146	297	205	498
Comprehensive income (loss)		210	166	351	367
Reportable Legal Entities [Member] | Assured Guaranty Ltd. (Parent) [Member]
Revenues
Net earned premiums		0	0	0	0
Net investment income		0	0	0	0
Net realized investment gains (losses)		0	0	0	0
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements		0	0	0	0
Net unrealized gains (losses)		0	0	0	0
Net change in fair value of credit derivatives		0	0	0	0
Bargain purchase gain and settlement of pre-existing relationships			0		0
Other		0	0	0	0
Total revenues		0	0	0	0
Expenses
Loss and LAE		0	0	0	0
Amortization of DAC		0	0	0	0
Interest expense		0	0	0	0
Other operating expenses		8	9	16	17
Total expenses		8	9	16	17
Income (loss) before income taxes		(8)	(9)	(16)	(17)
Total (provision) benefit for income taxes		0	0	0	0
Equity in net earnings of subsidiaries		154	306	221	515
Net income (loss)		146	297	205	498
Less: noncontrolling interest		0	0	0	0
Net income (loss)		146	297	205	498
Comprehensive income (loss)		210	166	351	367
Reportable Legal Entities [Member] | AGUS (Issuer) [Member]
Revenues
Net earned premiums		0	0	0	0
Net investment income		0	0	0	0
Net realized investment gains (losses)		0	0	0	0
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements		0	0	0	0
Net unrealized gains (losses)		0	0	0	0
Net change in fair value of credit derivatives		0	0	0	0
Bargain purchase gain and settlement of pre-existing relationships			0		0
Other		0	0	0	0
Total revenues		0	0	0	0
Expenses
Loss and LAE		0	0	0	0
Amortization of DAC		0	0	0	0
Interest expense		13	13	26	26
Other operating expenses		0	1	0	1
Total expenses		13	14	26	27
Income (loss) before income taxes		(13)	(14)	(26)	(27)
Total (provision) benefit for income taxes		4	4	9	9
Equity in net earnings of subsidiaries		140	305	190	468
Net income (loss)		131	295	173	450
Less: noncontrolling interest		0	0	0	0
Net income (loss)		131	295	173	450
Comprehensive income (loss)		166	210	246	344
Reportable Legal Entities [Member] | AGMH (Issuer) [Member]
Revenues
Net earned premiums		0	0	0	0
Net investment income		0	0	0	0
Net realized investment gains (losses)		0	1	0	1
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements		0	0	0	0
Net unrealized gains (losses)		0	0	0	0
Net change in fair value of credit derivatives		0	0	0	0
Bargain purchase gain and settlement of pre-existing relationships			0		0
Other		0	0	0	0
Total revenues		0	1	0	1
Expenses
Loss and LAE		0	0	0	0
Amortization of DAC		0	0	0	0
Interest expense		14	14	27	27
Other operating expenses		0	0	1	0
Total expenses		14	14	28	27
Income (loss) before income taxes		(14)	(13)	(28)	(26)
Total (provision) benefit for income taxes		5	4	10	9
Equity in net earnings of subsidiaries		113	122	190	214
Net income (loss)		104	113	172	197
Less: noncontrolling interest		0	0	0	0
Net income (loss)		104	113	172	197
Comprehensive income (loss)		125	50	217	130
Reportable Legal Entities [Member] | Other Entities [Member]
Revenues
Net earned premiums		222	226	414	366
Net investment income		98	101	198	205
Net realized investment gains (losses)		10	(10)	(2)	9
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements		24	8	32	29
Net unrealized gains (losses)		39	108	(29)	211
Net change in fair value of credit derivatives		63	116	3	240
Bargain purchase gain and settlement of pre-existing relationships			54		54
Other		11	83	47	69
Total revenues		404	570	660	943
Expenses
Loss and LAE		104	184	197	202
Amortization of DAC		7	8	14	14
Interest expense		2	3	5	7
Other operating expenses		55	57	107	105
Total expenses		168	252	323	328
Income (loss) before income taxes		236	318	337	615
Total (provision) benefit for income taxes		(65)	(78)	(81)	(150)
Equity in net earnings of subsidiaries		14	11	23	20
Net income (loss)		185	251	279	485
Less: noncontrolling interest		14	11	23	20
Net income (loss)		171	240	256	465
Comprehensive income (loss)		248	122	426	355
Consolidating Adjustments [Member]
Revenues
Net earned premiums		(8)	(7)	(17)	(5)
Net investment income		0	(3)	(1)	(6)
Net realized investment gains (losses)		0	0	(1)	(3)
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements		0	0	0	0
Net unrealized gains (losses)		0	(26)	0	(26)
Net change in fair value of credit derivatives		0	(26)	0	(26)
Bargain purchase gain and settlement of pre-existing relationships			160		160
Other		0	0	0	0
Total revenues		(8)	124	(19)	120
Expenses
Loss and LAE		(2)	4	(5)	4
Amortization of DAC		(2)	(2)	(5)	(4)
Interest expense		(4)	(4)	(7)	(9)
Other operating expenses		0	(1)	(1)	(1)
Total expenses		(8)	(3)	(18)	(10)
Income (loss) before income taxes		0	127	(1)	130
Total (provision) benefit for income taxes		1	(42)	1	(45)
Equity in net earnings of subsidiaries		(421)	(744)	(624)	(1,217)
Net income (loss)		(420)	(659)	(624)	(1,132)
Less: noncontrolling interest		(14)	(11)	(23)	(20)
Net income (loss)		(406)	(648)	(601)	(1,112)
Comprehensive income (loss)		$ (539)	$ (382)	$ (889)	$ (829)

[1] Excludes $3 million and $5 million for Second Quarter 2016 and 2015, respectively, and $8 million and $10 million for Six Months 2016 and 2015, respectively, related to consolidated FG VIEs.