Goodwill and Other Intangibles - Summary of the Company’s intangible assets other than goodwill (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Schedule of Finite and Indefinite Lived Intangible Assets [Line Items]
Weighted average amortization period	10 years
Finite-lived intangible assets, gross	$ 50,898	$ 52,601
Accumulated amortization, finite-lived intangible assets	(41,785)	(38,739)
Net book value	9,113	13,862
Total intangible assets at net book value	10,013	14,762
Customer Relationships [Member]
Schedule of Finite and Indefinite Lived Intangible Assets [Line Items]
Weighted average amortization period	10 years
Finite-lived intangible assets, gross	42,883	43,859
Accumulated amortization, finite-lived intangible assets	(33,770)	(30,153)
Internally Developed Software [Member]
Schedule of Finite and Indefinite Lived Intangible Assets [Line Items]
Weighted average amortization period	7 years
Finite-lived intangible assets, gross	8,015	8,742
Accumulated amortization, finite-lived intangible assets	(8,015)	(8,586)
Trade Names [Member]
Schedule of Finite and Indefinite Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 900	$ 900