Acquisitions - National Meter (Details) - USD ($) $ in Thousands			12 Months Ended
	Aug. 17, 2015	Oct. 01, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition
Goodwill			$ 47,978	$ 47,722	$ 44,700
National Meter and Automation, Inc.
Business Acquisition
Percentage acquired		100.00%
Incremental revenue		$ 15,000
Total purchase consideration		22,900
Cash payment		20,300
Deferred payments			2,500
Receivables		3,900
Inventory		4,500
Property, plant and equipment		2,800
Intangibles		9,800
Goodwill		3,000
Current liabilities		$ 100
Transaction costs			400
Accounts Payable | National Meter and Automation, Inc.
Business Acquisition
Deferred payments			2,000
Long-term Debt | National Meter and Automation, Inc.
Business Acquisition
Deferred payments			$ 500
Customer relationships | National Meter and Automation, Inc.
Business Acquisition
Estimated average useful life (in years)			12 years
National Meter and Automation, Inc. | United Utilities, Inc.
Business Acquisition
Total purchase consideration	$ 3,300
Cash payment	400
Receivables			$ 800
Inventory			400
Property, plant and equipment			100
Intangibles			1,700
Goodwill			$ 300
Receivables	$ 2,900
National Meter and Automation, Inc. | Customer relationships | United Utilities, Inc.
Business Acquisition
Estimated average useful life (in years)			12 years