Outstanding Exposure - Expected Amortization of Net Par Outstanding (Details) - USD ($) $ in Millions	Dec. 31, 2016		Dec. 31, 2015
Expected Amortization of Net Par Outstanding [Abstract]
0 to 5 years	$ 106,957
5 to 10 years	60,043
10 to 15 years	48,260
15 to 20 years	38,916
20 years and above	42,142
Net Par Outstanding	296,318	[1]	$ 358,571	[2]
Public Finance [Member]
Expected Amortization of Net Par Outstanding [Abstract]
0 to 5 years	90,563
5 to 10 years	56,351
10 to 15 years	45,712
15 to 20 years	37,057
20 years and above	41,496
Net Par Outstanding	271,179		321,443
Structured Finance [Member]
Expected Amortization of Net Par Outstanding [Abstract]
0 to 5 years	16,394
5 to 10 years	3,692
10 to 15 years	2,548
15 to 20 years	1,859
20 years and above	646
Net Par Outstanding	$ 25,139		$ 37,128

[1] The December 31, 2016 amounts include $2.9 billion of net par from the CIFG Acquisition.

[2] The December 31, 2015 amounts include $10.9 billion of net par from the Radian Asset Acquisition.