Unaudited Condensed COnsolidated Statements of Income - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Net sales $ 279,836 $ 248,774 $ 1,027,447 $ 917,760 $ 719,509
Cost of sales 156,604 149,240 608,616 550,893 421,897
Gross profit 123,232 99,534 418,831 366,867 297,612
Selling, general and administrative expenses 59,756 47,399 226,716 187,864 138,986
Provision for legal settlement     32,000 0 0
Operating income 63,476 52,135 160,115 179,003 158,626
Interest expense     15,091 13,887 20,640
Interest expense, net 3,637 3,683      
Loss on extinguishment of debt     0 0 15,918
Interest income     (294) (173) (125)
Income before income taxes 59,839 48,452 145,318 165,289 122,193
Provision for income taxes 22,506 18,406 55,930 63,358 43,957
Net income $ 37,333 $ 30,046 $ 89,388 $ 101,931 $ 78,236
Basic net income per common share $ 0.19 $ 0.15 $ 0.46 $ 0.52 $ 0.40
Diluted net income per common share $ 0.19 $ 0.15 $ 0.45 $ 0.52 $ 0.40
Basic weighted average shares 196,217,311 195,745,670 195,933,800 195,735,309 195,619,943
Diluted weighted average shares 198,160,465 197,773,850 198,047,453 197,852,932 196,559,084