Acquisitions (Narrative) (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
	Jun. 09, 2015	Sep. 30, 2013	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Remaining purchase adjustment				$ 2,314
Goodwill				292,390	$ 236,044	$ 341,174
Rough Brothers Incorporated
Business Acquisition [Line Items]
Acquisition purchase price	$ 147,585
Working capital adjustment	6,302
Goodwill	57,180
Tax deductible goodwill	37,969
Indemnification assets	3,000
Fair value of purchase consideration	$ 147,585
2013 Acquisitions
Business Acquisition [Line Items]
Goodwill					2,466
Fair value of purchase consideration		$ 7,454			7,454
Payment for aggregate purchase consideration		$ 2,322		61	368
2013 Acquisitions | SG&A
Business Acquisition [Line Items]
Adjustment to payable, expense recorded				(480)	(1,611)
2013 Acquisitions | Interest Expense
Business Acquisition [Line Items]
Adjustment to payable, expense recorded				$ 8	$ 75
2013 Acquisitions | Interest Expense | Forecast
Business Acquisition [Line Items]
Final remittance payment			$ 61