Segment Information (Reportable Segment Financial Results) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Total revenue		$ 183,063	$ 158,811	$ 532,510	$ 462,063
Total segment operating income		13,540	13,968	37,776	36,441
Corporate unallocated costs	[1]	(53,236)	(47,975)	(156,013)	(141,162)
Stock-based compensation costs		(8,818)	(6,486)	(25,005)	(17,899)
Amortization expense		(10,549)	(8,069)	(31,817)	(24,286)
Interest expense		(2,641)	(1,816)	(8,037)	(5,375)
Other (expense) income, net		(15)	192	(185)	(1,369)
Income before provision for income taxes		10,884	12,344	29,554	29,697
GMBU [Member]
Segment Reporting Information [Line Items]
Total revenue		97,621	78,244	279,543	224,311
Total segment operating income	[2]	46,540	40,718	134,408	114,719
ECBU [Member]
Segment Reporting Information [Line Items]
Total revenue		74,351	69,326	220,887	205,625
Total segment operating income	[2]	38,696	33,568	113,186	99,522
IBU [Member]
Segment Reporting Information [Line Items]
Total revenue		11,030	11,181	31,926	31,995
Total segment operating income	[2]	1,064	2,431	3,126	5,823
Other [Member]
Segment Reporting Information [Line Items]
Total revenue	[3]	61	60	154	132
Total segment operating income	[2],[3]	(157)	(219)	(109)	(276)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total segment operating income		$ 86,143	$ 76,498	$ 250,611	$ 219,788

[1] Corporate unallocated costs include research and development, depreciation expense, and certain corporate sales, marketing, general and administrative expenses.

[2] Segment operating income includes direct, controllable costs related to the sale of solutions and services by the reportable segment.

[3] Other includes revenue and the related costs from the sale of solutions and services not directly attributable to a reportable segment.