Intangible Assets Schedule of Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Schedule of Intangible Assets [Abstract]

Schedule of Finite-Lived Intangible Assets [Table Text Block]

The gross carrying amount and accumulated amortization of our intangible assets, other than goodwill, are as follows:

	December 31, 2017							December 31, 2016
	Gross Assets		Accumulated Amortization			Net		Gross Assets		Accumulated Amortization			Net
	(in thousands)
Core-developed technology	$	429,548	$	(399,969	)	$	29,579	$	372,568	$	(354,878	)	$	17,690
Customer contracts and relationships	258,586		(197,582		)	61,004		224,467		(170,056		)	54,411
Trademarks and trade names	70,056		(66,004		)	4,052		61,785		(61,766		)	19
Other	11,661		(11,068		)	593		11,076		(11,045		)	31
Total intangible assets	$	769,851	$	(674,623	)	$	95,228	$	669,896	$	(597,745	)	$	72,151

SummaryOfIntangibleAssetAccountActivity [Table Text Block]

A summary of the intangible asset account activity is as follows:

	Year Ended December 31,
	2017		2016
	(in thousands)
Beginning balance, intangible assets, gross	$	669,896	$	702,507
Intangible assets acquired	36,500		—
Effect of change in exchange rates	63,455		(32,611		)
Ending balance, intangible assets, gross	$	769,851	$	669,896

Finite-lived Intangible Assets Amortization Expense [Table Text Block]

A summary of intangible asset amortization expense is as follows:

	Year Ended December 31,
	2017		2016		2015
	(in thousands)
Amortization expense	$	20,785	$	25,112	$	31,673

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

Estimated future annual amortization expense is as follows:

Year Ending December 31,	Estimated Annual Amortization
	(in thousands)
2018	$	19,380
2019	16,553
2020	14,208
2021	12,162
2022	9,961
Beyond 2022	22,964
Total intangible assets subject to amortization	$	95,228