10. Intangible Assets

Intangible assets at December 31, 2015 and 2014 consisted of the following:

(in millions)	Remaining Weighted- Average Estimated Useful Life		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
At December 31, 2015
Indefinite-lived intangible assets:
Management contracts	N/A		$	15,699	$	—	$	15,699
Trade names / trademarks	N/A			1,403		—		1,403
License	N/A			6		—		6
Total indefinite-lived intangible assets				17,108		—		17,108
Finite-lived intangible assets:
Management contracts		3.7		1,003		741		262
Intellectual property		2.6		6		4		2
Total finite-lived intangible assets		3.7		1,009		745		264
Total intangible assets			$	18,117	$	745	$	17,372
At December 31, 2014
Indefinite-lived intangible assets:
Management contracts	N/A		$	15,579	$	—	$	15,579
Trade names / trademarks	N/A			1,403		—		1,403
License	N/A			6		—		6
Total indefinite-lived intangible assets				16,988		—		16,988
Finite-lived intangible assets:
Management contracts		3.8		1,390		1,036		354
Intellectual property		3.6		6		4		2
Total finite-lived intangible assets		3.8		1,396		1,040		356
Total intangible assets			$	18,384	$	1,040	$	17,344

N/A	— Not Applicable

The impairment tests performed for intangible assets as of July 31, 2015, 2014 and 2013 indicated no impairment charges were required.

Estimated amortization expense for finite-lived intangible assets for each of the five succeeding years is as follows:

(in millions)
Year	Amount
2016	$	97
2017		80
2018		30
2019		28
2020		14

Indefinite-Lived Acquired Management Contracts

In March 2015, in connection with the BKCA acquisition, the Company acquired $120 million of indefinite-lived management contracts.

Finite-Lived Acquired Management Contracts

In October 2015, in connection with the Infraestructura Institucional acquisition, the Company acquired $36 million of finite-lived management contracts with a weighted-average estimated useful life of approximately six years.