Goodwill and intangible assets (Tables)

12 Months Ended

Dec. 31, 2012

Goodwill and intangible assets

Schedule of changes in carrying amount of goodwill and intangible assets

The changes in the carrying amount of goodwill and intangible assets for the year ended December 31, 2012 are as follows:

	Balance as of December 31, 2011		Additions		Amortization			Balance as of December 31, 2012
Goodwill	$	25,512	$	1,232	$	—		$	26,744
Intangible assets subject to amortization		9,846		1,851		(1,103	)		10,594
Total	$	35,358	$	3,083	$	(1,103	)	$	37,338

        The changes in the carrying amount of goodwill and intangible assets for the year ended December 31, 2011 are as follows:

	Balance as of December 31, 2010		Additions		Amortization			Balance as of December 31, 2011
Goodwill	$	25,512	$	—	$	—		$	25,512
Intangible assets subject to amortization		11,251		250		(1,655	)		9,846
Total	$	36,763	$	250	$	(1,655	)	$	35,358

Schedule of intangible assets

        Intangible assets at December 31, 2012 consist of the following:

	Weighted Average Life	Historical Cost		Accumulated Amortization			Net
Venue contracts	11 years	$	26,886	$	(17,783	)	$	9,103
Technology	5 years		1,110		(93	)		1,017
Advertiser relationships	5 years		70		(6	)		64
Patents, trademarks and other	5 years		839		(429	)		410
Total		$	28,905	$	(18,311	)	$	10,594

        Intangible assets at December 31, 2011 consist of the following:

	Weighted Average Life	Historical Cost		Accumulated Amortization			Net
Venue contracts	11 years	$	26,385	$	(16,874	)	$	9,511
Patents, trademarks and other	6 years		391		(56	)		335
		$	26,776	$	(16,930	)	$	9,846

Schedule of amortization expense for fiscal years 2013 through 2017 and thereafter

        Amortization expense for fiscal years 2013 through 2017 and thereafter is as follows:

Year	Amortization Expense
2013	$	1,220
2014		1,175
2015		1,127
2016		1,092
2017		970
Thereafter		5,010
	$	10,594