7. Intangible Assets

The changes in the carrying amount of goodwill and intangible assets for the Company between January 1, 2013 and December 31, 2013 are as follows:


(in $ millions)	January 1, 2013			Additions			Retirements			Foreign Exchange			December 31, 2013
Non-Amortizable Assets:
Goodwill		986			—			—			—			986
Trademarks and tradenames		314			—			—			—			314
Other Intangible Assets:
Acquired customer relationships		1,129			—			—			—			1,129
Accumulated amortization		(530	)		(80	)		—			—			(610	)

Acquired customer relationships, net		599			(80	)		—			—			519

Customer loyalty payments		274			98			(66	)		—			306
Accumulated amortization		(156	)		(63	)		66			(1	)		(154	)

Customer loyalty payments, net		118			35			—			(1	)		152

Other intangible assets, net		717			(45	)		—			(1	)		671


The changes in the carrying amount of goodwill and intangible assets for the Company between January 1, 2012 and December 31, 2012 are as follows:
(in $ millions)	January 1, 2012			Additions			Retirements			Foreign Exchange			December 31, 2012
Non-Amortizable Assets:
Goodwill		986			—			—			—			986
Trademarks and tradenames		314			—			—			—			314
Other Intangible Assets:
Acquired customer relationships		1,129			—			—			—			1,129
Accumulated amortization		(448	)		(82	)		—			—			(530	)

Acquired customer relationships, net		681			(82	)		—			—			599

Customer loyalty payments		269			50			(45	)		—			274
Accumulated amortization		(140	)		(62	)		45			1			(156	)

Customer loyalty payments, net		129			(12	)		—			1			118

Other intangible assets, net		810			(94	)		—			1			717

The Company paid cash of $78 million and $47 million for customer loyalty payments during the years ended December 31, 2013 and 2012, respectively. Further, as of December 31, 2013 and 2012, the Company had a balance payable of $35 million and $15 million, respectively, for customer loyalty payments (see Note 9).

Customer loyalty payments are payments made to travel agents or travel providers with an objective of increasing the number of travel bookings using the Company’s GDS and to improve the travel agents’ or travel providers’ loyalty, which are instrumented through agreements with a term over a year. Under the contractual terms, the travel agent or travel provider commits to achieve certain economic objectives for the Company. Such costs are specifically identifiable to individual contracts with travel agents or travel providers, which have determinable contractual lives. Due to the contractual nature of the payments, the Company believes that such assets are more appropriately classified as intangible assets and, as a result, the Company has presented them within intangible assets with conforming changes to prior periods. As of December 31 2012, the Company included $50 million and $68 million net development advances within other current assets and other non-current assets, respectively, which have been re-classed as other intangible assets to conform to current period presentation.

Amortization expense for acquired customer relationships was $80 million, $82 million and $88 million for the years ended December 31, 2013, 2012 and 2011, respectively, and is included as a component of depreciation and amortization on the Company’s consolidated statements of operations.

Amortization expense for customer loyalty payments was $63 million, $62 million and $74 million for the years ended December 31, 2013, 2012 and 2011, respectively, and is included within revenue or cost of revenue in the Company’s consolidated statements of operations.

The Company expects amortization expense relating to acquired customer relationships and customer loyalty payments balances as of December 31, 2013 to be:


	Year Ending December 31,
(in $ millions)	Acquired Customer Relationships		Customer Loyalty Payments
2014		76		59
2015		68		39
2016		39		22
2017		42		14
2018		41		7