Employee Benefit Plans - Badger Meter Employee Savings and Stock Ownership Plan (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2010
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Loans payable	$ 500			$ 1,500
Principal payments	$ 154	$ 154	$ 154
Shares contributed to ESOP (in shares)	19,417	11,583	10,157
Unreleased shares in ESOP (in shares)	81,827	101,244	124,410
Fair value of unreleased shares	$ 3,900	$ 3,700	$ 3,600
Pretax income allowed to be deferred (as a percent)	20.00%
Company match (as a percent)	25.00%
Maximum match of employee's salary (as a percent)	7.00%
Compensation expense	$ 500	$ 400	$ 400
Employee Stock Ownership Plan (ESOP), Plan | Loans Receivable
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Loan to repay third party loan				500
Additional loan to ESOP				1,000
Loans payable	500			$ 1,500
Defined Contribution Feature
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Compensation expense	$ 2,800