Goodwill and Other Intangibles Additional Information (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Goodwill	$ 64,493	$ 61,680
Credo [Member]
Business Acquisition [Line Items]
Goodwill	60,619
Water Resource Company [Member]
Business Acquisition [Line Items]
Goodwill	3,874
Goodwill and other intangible assets	1,667
Patents [Member] | Credo [Member]
Business Acquisition [Line Items]
Identified intangible assets acquired	590
Goodwill and other intangible assets	$ 496