Goodwill and Finite Life Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013 item	Jun. 30, 2012	Jun. 30, 2013 unit	Jun. 30, 2012	Dec. 31, 2012 item
Goodwill and Finite Life Intangible Assets
Number of operating units			1
Number of reporting units			1
Goodwill	$ 37,780		$ 37,780		$ 37,780
Impairment of goodwill					0
Number of triggering events that occurred	0				0
Identified intangible assets
Gross Assets	32,570		32,570		32,570
Accumulated Amortization	(15,633)		(15,633)		(11,810)
Net Assets	16,937		16,937		20,760
Amortization expenses	1,841	619	3,823	1,238
Future amortization expenses for the next five years
Remainder of 2013	3,428		3,428
2014	5,293		5,293
2015	3,963		3,963
2016	2,937		2,937
2017	1,316		1,316
Net Assets	16,937		16,937		20,760
Customer relationships
Identified intangible assets
Gross Assets	29,133		29,133		29,133
Accumulated Amortization	(12,399)		(12,399)		(8,665)
Net Assets	16,734		16,734		20,468
Amortization expenses	1,797	553	3,735	1,106
Future amortization expenses for the next five years
Net Assets	16,734		16,734		20,468
Customer relationships | Minimum
Identified intangible assets
Amortizable Period			5 years
Customer relationships | Maximum
Identified intangible assets
Amortizable Period			8 years
Services agreement
Identified intangible assets
Amortizable Period			4 years
Gross Assets	67		67		67
Accumulated Amortization	(63)		(63)		(54)
Net Assets	4		4		13
Amortization expenses	4	4	8	8
Future amortization expenses for the next five years
Net Assets	4		4		13
Certification
Identified intangible assets
Amortizable Period			2 years
Gross Assets	467		467		467
Accumulated Amortization	(467)		(467)		(467)
Covenant not to compete
Identified intangible assets
Amortizable Period			3 years
Gross Assets	478		478		478
Accumulated Amortization	(279)		(279)		(199)
Net Assets	199		199		279
Amortization expenses	40	40	80	80
Future amortization expenses for the next five years
Net Assets	199		199		279
Trademarks
Identified intangible assets
Amortizable Period			3 years
Gross Assets	263		263		263
Accumulated Amortization	(263)		(263)		(263)
Amortization expenses		22		44
Order backlog
Identified intangible assets
Gross Assets	2,162		2,162		2,162
Accumulated Amortization	$ (2,162)		$ (2,162)		$ (2,162)
Order backlog | Minimum
Identified intangible assets
Amortizable Period			3 months
Order backlog | Maximum
Identified intangible assets
Amortizable Period			1 year