6. Intangible Assets

The changes in the carrying amount of goodwill and intangible assets for the Company between January 1, 2014 and June 30, 2014 are as follows:


(in $ millions)	January 1, 2014			Additions			Retirements			Foreign Exchange		June 30, 2014
Non-Amortizable Assets:
Goodwill	$	986		$	14		$	—		$	—	$	1,000
Trademarks and tradenames		314			—			—			—		314
Other Intangible Assets:
Acquired intangible assets		1,129			—			—			1		1,130
Accumulated amortization		(610	)		(39	)		—			—		(649	)

Acquired intangible assets, net		519			(39	)		—			1		481

Customer loyalty payments		306			72			(44	)		1		335
Accumulated amortization		(154	)		(37	)		44			—		(147	)

Customer loyalty payments, net		152			35			—			1		188

Other intangible assets, net	$	671		$	(4	)	$	—		$	2	$	669

The changes in the carrying amount of goodwill and intangible assets for the Company between January 1, 2013 and June 30, 2013 are as follows:


(in $ millions)	January 1, 2013			Additions			Retirements			Foreign Exchange			June 30, 2013
Non-Amortizable Assets:
Goodwill	$	986		$	—		$	—		$	—		$	986
Trademarks and tradenames		314			—			—			—			314
Other Intangible Assets:
Acquired intangible assets		1,129			—			—			—			1,129
Accumulated amortization		(530	)		(40	)		—			—			(570	)

Acquired intangible assets, net		599			(40	)		—			—			559

Customer loyalty payments		274			36			(50	)		(3	)		257
Accumulated amortization		(156	)		(29	)		50			—			(135	)

Customer loyalty payments, net		118			7			—			(3	)		122

Other intangible assets, net	$	717		$	(33	)	$	—		$	(3	)	$	681

In May 2014, the Company made an acquisition for $14 million, of which $10 million was paid in cash and $4 million is deferred consideration to be paid upon resolution of certain items. The acquisition resulted in goodwill of $14 million. As of June 30, 2014, the Company is in the process of allocating the purchase consideration to acquired identifiable assets and liabilities.

The Company paid cash of $45 million and $36 million for customer loyalty payments during the six months ended June 30, 2014 and 2013, respectively. Further, as of June 30, 2014 and December 31, 2013, the Company had balances payable of $62 million and $35 million, respectively, for customer loyalty payments (see Note 8).

Amortization expense for acquired intangible assets, which consists of customer relationships, was $20 million for both of the three months ended June 30, 2014 and 2013, respectively, and $39 million and $40 million for the six months ended June 30, 2014 and 2013, respectively, and is included as a component of depreciation and amortization on the Company’s consolidated condensed statements of operations.

Amortization expense for customer loyalty payments was $19 million and $15 million for the three months ended June 30, 2014 and 2013, respectively, and $37 million and $29 million for the six months ended June 30, 2014 and 2013, respectively, and is included within cost of revenue or revenue in the Company’s consolidated condensed statements of operations.