Significant Accounting Policies (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 item	Dec. 31, 2013	Dec. 31, 2012
Information about the operations in different geographical areas
Number of facilities through which services are provided									30
Revenues
Revenues	$ 146,518	$ 134,121	$ 140,310	$ 132,727	$ 152,179	$ 134,973	$ 140,105	$ 132,352	$ 553,676	$ 559,609	$ 581,091
Property, plant and equipment
Property, Plant and Equipment, Net	36,913				40,711				36,913	40,711
United States
Revenues
Revenues									463,752	469,596	492,118
Property, plant and equipment
Property, Plant and Equipment, Net	33,134				34,556				33,134	34,556
Other countries
Information about the operations in different geographical areas
Number of facilities through which services are provided									8
Revenues
Revenues									89,924	90,013	88,973
Property, plant and equipment
Property, Plant and Equipment, Net	$ 3,779				$ 6,155				$ 3,779	$ 6,155