Selected Quarterly Financial Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Selected Quarterly Financial Information [Abstract]
Net sales	$ 223,671	$ 233,777	$ 223,217	$ 209,986	$ 210,993	$ 224,510	$ 214,379	$ 176,964	$ 890,651	$ 826,846	$ 633,806
Gross profit	70,662	74,732	70,304	61,581	60,801	69,559	61,293	46,183	277,279	237,836	161,586
Net income (loss) attributable to common shareholders	$ 16,665	$ 19,427	$ 17,385	$ 10,202	$ 6,204	$ 13,619	$ 8,635	$ (1,926)	$ 63,678	$ 26,532	$ 24,152
Earnings (loss) per share attributable to common shareholders
Basic	$ 0.35	$ 0.41	$ 0.37	$ 0.22	$ 0.13	$ 0.29	$ 0.19	$ (0.04)	$ 1.35	$ 0.57	$ 0.53
Diluted	$ 0.34	$ 0.40	$ 0.36	$ 0.21	$ 0.13	$ 0.28	$ 0.18	$ (0.04)	$ 1.31	$ 0.56	$ 0.51