Acquisitions (Wolverine - Pro Forma Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Net income	$ 25,170
Wolverine and Wolverine Joining
Business Acquisition [Line Items]
Net sales		596,314	581,257
Net income		$ 43,358	$ 28,603
Net income per share (in dollars per share)		$ 3.27	$ 2.19
Weighted-average number of common shares outstanding		13,251	13,032