Selected Quarterly Financial Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Selected Quarterly Financial Information [Abstract]
Net sales	$ 143,313	$ 160,577	$ 169,806	$ 161,555	$ 163,767	$ 163,120	$ 149,153	$ 136,847	$ 635,251	$ 612,886	$ 434,357
Gross profit	35,495	45,194	55,615	57,393	62,643	60,977	53,467	47,783	193,697	224,869	121,207
Net income attributable to common stockholders	$ 3,115	$ 9,957	$ 17,981	$ 19,684	$ 23,967	$ 21,162	$ 16,647	$ 14,958	$ 50,737	$ 76,733	$ 7,513
Earnings per share attributable to common shareholders
Basic	$ 0.07	$ 0.22	$ 0.38	$ 0.44	$ 0.54	$ 0.48	$ 0.38	$ 0.34	$ 1.12	$ 1.74	$ 0.18
Diluted	$ 0.07	$ 0.21	$ 0.37	$ 0.42	$ 0.52	$ 0.46	$ 0.37	$ 0.33	$ 1.09	$ 1.68	$ 0.17