6. Goodwill and Other intangible assets

At December 31, 2017 and 2016, Goodwill was $15.5 billion and $15.3 billion, respectively, and Other intangible assets were $6.5 billion and $6.8 billion, respectively.

a) Goodwill

The following table presents a roll-forward of Goodwill by segment:



(in millions of U.S. dollars)	North America Commercial P&C Insurance		North America Personal P&C Insurance		North America Agricultural Insurance		Overseas General Insurance			Global Reinsurance		Life Insurance		Chubb Consolidated
Balance at December 31, 2015	$	1,203	$	196	$	134	$	2,078		$	365	$	820	$	4,796
Acquisition of Chubb Corp	5,714		2,025		—		2,775			—		—		10,514
Foreign exchange revaluation and other	44		14		—		(36		)	—		—		22
Balance at December 31, 2016	$	6,961	$	2,235	$	134	$	4,817		$	365	$	820	$	15,332
Foreign exchange revaluation and other	15		5		—		187			—		2		209
Balance at December 31, 2017	$	6,976	$	2,240	$	134	$	5,004		$	365	$	822	$	15,541

b) Other intangible assets

The majority of the Other intangible assets balance at December 31, 2017 relates to the Chubb Corp acquisition and comprised of $3.5 billion that are subject to amortization, principally Agency distribution relationships and renewal rights, and $3.0 billion that are not subject to amortization, principally trademarks. This compares to $3.8 billion and $3.0 billion at December 31, 2016, respectively.

Amortization of purchased intangibles

Amortization expense related to purchased intangibles amounted to $260 million, $19 million, and $171 million for the years ended December 31, 2017, 2016, and 2015, respectively. The increase in amortization expense of purchased intangibles primarily reflects higher intangible amortization expense related to agency distribution relationships and renewal rights and lower amortization benefit from the fair value adjustment on Unpaid losses and loss expenses, both related to the Chubb Corp acquisition.

The following table presents, as of December 31, 2017, the expected estimated pre-tax amortization expense (benefit) of purchased intangibles, at current foreign currency exchange rates, for the next five years:



	Associated with the Chubb Corp Acquisition
For the Year Ending December 31 (in millions of U.S. dollars)	Agency distribution relationships and renewal rights		Internally developed technology		Fair value adjustment on Unpaid losses and loss expense ⁽¹⁾			Total		Other intangible assets		Total Amortization of purchased intangibles
2018	$	325	$	32	$	(102	)	$	255	$	83	$	338
2019	282		—		(63		)	219		75		294
2020	241		—		(36		)	205		67		272
2021	218		—		(20		)	198		61		259
2022	198		—		(14		)	184		57		241
Total	$	1,264	$	32	$	(235	)	$	1,061	$	343	$	1,404

⁽¹⁾

In connection with the Chubb Corp acquisition, we recorded an increase to Unpaid losses and loss expenses acquired to adjust the carrying value of Chubb Corp's historical unpaid losses and loss expenses to fair value as of the acquisition date. This fair value adjustment amortizes through Amortization of purchased intangibles on the Consolidated statements of operations over a range of 5 to 17 years. The balance of the fair value adjustment on Unpaid losses and loss expense at December 31, 2017 was $309 million. Refer to Note 1(h) for additional information.

c) VOBA

The following table presents a roll-forward of VOBA:



(in millions of U.S. dollars)	2017			2016			2015
Balance, beginning of year	$	355		$	395		$	466
Amortization of VOBA ⁽¹⁾	(35		)	(41		)	(42		)
Foreign exchange revaluation	6			1			(29		)
Balance, end of year	$	326		$	355		$	395


⁽¹⁾	Recognized in Policy acquisition costs in the Consolidated statements of operations.

The following table presents, as of December 31, 2017, the expected estimated pre-tax amortization expense related to VOBA for the next five years:



For the Year Ending December 31	VOBA
(in millions of U.S. dollars)	VOBA
2018	$	32
2019	27
2020	25
2021	22
2022	20
Total	$	126