Recent Accounting Pronouncements - Impact on Unaudited Condensed Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues
Revenues	$ 123,933	$ 123,738	$ 366,672	$ 351,783
Cost of revenues
Cost of Goods and Services Sold	79,183	81,139	238,004	233,718
Income from operations	9,261	10,957	24,543	24,041
Net income	6,305	7,027	17,083	12,146
Services
Revenues
Revenues	122,879	117,415	363,986	329,192
Cost of revenues
Cost of Goods and Services Sold	79,183	75,971	238,004	214,858
Software and hardware
Revenues
Revenues	1,054	6,323	2,686	22,591
Cost of revenues
Cost of Goods and Services Sold	0	$ 5,168	0	$ 18,860
Impact of ASC Topic 606 Adoption | ASU 2014-09
Revenues
Revenues	3,665		16,050
Cost of revenues
Cost of Goods and Services Sold	3,665		16,050
Income from operations	0		0
Net income	0		0
Impact of ASC Topic 606 Adoption | ASU 2014-09 | Services
Revenues
Revenues	0		0
Cost of revenues
Cost of Goods and Services Sold	0		0
Impact of ASC Topic 606 Adoption | ASU 2014-09 | Software and hardware
Revenues
Revenues	3,665		16,050
Cost of revenues
Cost of Goods and Services Sold	3,665		16,050
Without ASC Topic 606 Adoption | ASU 2014-09
Revenues
Revenues	127,598		382,722
Cost of revenues
Cost of Goods and Services Sold	82,848		254,054
Income from operations	9,261		24,543
Net income	6,305		17,083
Without ASC Topic 606 Adoption | ASU 2014-09 | Services
Revenues
Revenues	122,879		363,986
Cost of revenues
Cost of Goods and Services Sold	79,183		238,004
Without ASC Topic 606 Adoption | ASU 2014-09 | Software and hardware
Revenues
Revenues	4,719		18,736
Cost of revenues
Cost of Goods and Services Sold	$ 3,665		$ 16,050