Operating Segments and Related Information (Details 5) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 381,928	$ 375,366	$ 1,119,420	$ 1,096,288
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	216,200	192,500	587,600	559,100
Canada/Latin_America
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	23,825	20,870	60,224	69,349
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	66,207	82,253	255,331	256,908
Mid_East/Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	37,253	42,287	89,830	91,506
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 38,406	$ 37,461	$ 126,398	$ 119,467