Geographical Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenue and long-lived assets by geographical segments
Revenues	$ 91,977	$ 92,849
United States
Revenue and long-lived assets by geographical segments
Revenues	67,350	68,258
North America (Excluding U.S.)
Revenue and long-lived assets by geographical segments
Revenues	5,943	6,286
Europe, Middle East and Africa
Revenue and long-lived assets by geographical segments
Revenues	11,702	13,303
Asia Pacific
Revenue and long-lived assets by geographical segments
Revenues	5,667	4,303
Latin America
Revenue and long-lived assets by geographical segments
Revenues	$ 1,315	$ 699