Business Combination (Narrative) (Details) - USD ($)		2 Months Ended	3 Months Ended								12 Months Ended
	Nov. 04, 2015	Dec. 31, 2015	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill		$ 91,234,000	$ 91,234,000				$ 82,354,000				$ 91,234,000	$ 82,354,000	$ 83,397,000
Net income			46,529,000	$ 20,825,000	$ 45,083,000	$ 23,777,000	31,417,000	$ 9,382,000	$ 37,008,000	$ 13,174,000	136,214,000	90,981,000	93,644,000
Revenues			135,462,000	$ 109,318,000	$ 155,477,000	$ 115,618,000	$ 138,457,000	$ 102,217,000	$ 141,835,000	$ 98,588,000	515,875,000	$ 481,097,000	$ 467,403,000
Xcira LLC [Member]
Business Acquisition [Line Items]
Cash consideration	$ 12,359,000
Voting equity interests acquired, percentage	75.00%
Percentage ownership by non-controlling interest holders	25.00%
Contingent consideration	$ 0
Goodwill	10,659,000
Fair value of the non-controlling interest	$ 4,119,000
Net income		270,000
Revenues		871,000
Legal and other acquisition-related costs		410,000	410,000								410,000
Xcira LLC [Member] | Xcira Founder [Member]
Business Acquisition [Line Items]
Obligation to pay additional amount		2,000,000	2,000,000								$ 2,000,000
Period to make additional amount of obligation upon achievement of certain condition											3 years
Future Software Development [Member] | Xcira LLC [Member]
Business Acquisition [Line Items]
Obligation to pay additional amount		$ 2,700,000	$ 2,700,000								$ 2,700,000
Period to make additional amount of obligation upon achievement of certain condition											2 years