Acquisition (Details) - USD ($)		3 Months Ended	6 Months Ended		12 Months Ended
	Feb. 17, 2015	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Cash and stock consideration			$ 43,530,000	$ 0
Ahmann & Martin Co. [Member]
Business Acquisition [Line Items]
Cash and stock consideration	$ 48,000,000
Maximum contingent consideration	$ 8,000,000
Goodwill acquired			40,000,000
Increase in goodwill due to acquisition valuation adjustments		$ 70,000
Other Intangible Assets [Member]
Business Acquisition [Line Items]
Other intangible assets, additions during the period			12,115,000		$ 0
Other Intangible Assets [Member] | Ahmann & Martin Co. [Member]
Business Acquisition [Line Items]
Increase in intangible assets due to acquisition valuation adjustments		$ 500,000
Ahmann & Martin Co. [Member]
Business Acquisition [Line Items]
Other intangible assets, additions during the period			$ 12,000,000