Inventories - Schedule of Changes in Accounting Principles (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales	$ 100,058	$ 102,626
Net income	$ 14,928	$ 13,643
Basic earnings per share (in dollars per share)	$ 0.83	$ 0.74
Diluted earnings per share (in dollars per share)	$ 0.82	$ 0.72
As Originally Reported Under LIFO
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales		$ 102,696
Net income		$ 13,627
Basic earnings per share (in dollars per share)		$ 0.74
Diluted earnings per share (in dollars per share)		$ 0.72
Effect of Change
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales		$ (70)
Net income		$ 16
Basic earnings per share (in dollars per share)		$ 0.00
Diluted earnings per share (in dollars per share)		$ 0.00