Goodwill and Intangible Assets, Net

Changes in the carrying amount of goodwill were as follows:



(In millions)	U.S. Pharmaceutical and Specialty Solutions			European Pharmaceutical Solutions			Medical-Surgical Solutions		Other			Total
Balance, March 31, 2018	$	4,110		$	1,850		$	2,070	$	2,894		$	10,924
Goodwill acquired	—			52			360		12			424
Goodwill impairment charges	—			(570		)	—		(21		)	(591		)
Acquisition accounting, transfers and other adjustments	13			(4		)	16		6			31
Foreign currency translation adjustments, net	(49		)	(135		)	—		(85		)	(269		)
Balance, December 31, 2018	$	4,074		$	1,193		$	2,446	$	2,806		$	10,519

As of December 31, 2018, accumulated goodwill impairment losses were $1,736 million and $452 million in our European Pharmaceutical Solutions segment and Other. As of March 31, 2018, accumulated goodwill impairment losses were $1,299 million and $456 million in our European Pharmaceutical segment and Other. Refer to Financial Note 3, “Goodwill Impairment Charges,” for more information on goodwill impairment charges.

Information regarding intangible assets is as follows:



	December 31, 2018								March 31, 2018
(Dollars in millions)	Weighted Average Remaining Amortization Period (years)	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Customer relationships	12	$	3,980	$	(1,856	)	$	2,124	$	3,619	$	(1,550	)	$	2,069
Service agreements	11	1,011		(414		)	597		1,037		(386		)	651
Pharmacy licenses	25	767		(353		)	414		684		(196		)	488
Trademarks and trade names	13	884		(233		)	651		932		(187		)	745
Technology	4	139		(89		)	50		147		(84		)	63
Other	5	285		(201		)	84		262		(176		)	86
Total		$	7,066	$	(3,146	)	$	3,920	$	6,681	$	(2,579	)	$	4,102

Amortization expense of intangible assets was $122 million and $365 million for the third quarter and nine months ended December 31, 2018 and $123 million and $370 million for the third quarter and nine months ended December 31, 2017. Estimated annual amortization expense of these assets is as follows: $112 million, $429 million, $412 million, $379 million and $274 million for the remainder of 2019 and each of the succeeding years through 2023 and $2,314 million thereafter. All intangible assets were subject to amortization as of December 31, 2018 and March 31, 2018.

Refer to Financial Note 2, “Restructuring and Asset Impairment Charges,” for more information on intangible asset impairments recorded during the first quarter of 2019 for our U.K. retail business and the third quarter of 2019 for our Rexall Health retail business.