Business Combinations - Pro Forma (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Pro forma financial information:
Revenue	$ 1,848,351	$ 1,765,391
Net income	$ 140,468	146,091
Pro Forma
Business Acquisition [Line Items]
Transaction costs		1,800
Increase amortization expense		3,400
Increase in interest expense		7,600
Increase in depreciation expense		$ 4,500