Unaudited Quarterly Financial Data (Details) (USD $)	3 Months Ended								12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Unaudited Quarterly Financial Data [Abstract]
Net sales	$ 89,336,000	$ 116,275,000	$ 111,632,000	$ 89,023,000	$ 101,464,000	$ 84,097,000	$ 107,616,000	$ 70,510,000	$ 406,266,000	$ 363,687,000	$ 161,285,000
Cost of goods sold	86,486,000	92,232,000	94,911,000	76,909,000	94,188,000	85,678,000	92,637,000	63,477,000	350,538,000	335,980,000	109,903,000
Gross profit	2,850,000	24,043,000	16,721,000	12,114,000	7,276,000	(1,581,000)	14,979,000	7,033,000	55,728,000	27,707,000	51,382,000
Operating expenses [Abstract]
General and administrative	8,990,000	12,779,000	11,193,000	11,564,000	9,108,000	10,155,000	11,309,000	8,309,000	44,526,000	38,881,000	17,033,000
Sales and marketing	2,583,000	2,687,000	3,904,000	3,539,000	3,785,000	3,369,000	3,197,000	2,453,000	12,713,000	12,804,000	6,537,000
Research and development	924,000	807,000	461,000	436,000	495,000	453,000	401,000	416,000	2,628,000	1,765,000	1,549,000
Impairment of goodwill and intangible assets	84,686,000	0	0	0					84,686,000	0	0
Impairment of plant and equipment					0	1,031,000	0	0	0	1,031,000	0
Acquisition costs					0	0	309,000	404,000	0	713,000	879,000
Total operating expenses	97,183,000	16,273,000	15,558,000	15,539,000	13,388,000	15,008,000	15,216,000	11,582,000	144,553,000	55,194,000	25,998,000
Operating (loss) income	(94,333,000)	7,770,000	1,163,000	(3,425,000)	(6,112,000)	(16,589,000)	(237,000)	(4,549,000)	(88,825,000)	(27,487,000)	25,384,000
Other expense [Abstract]
Interest expense	7,271,000	5,889,000	6,162,000	5,084,000	5,690,000	3,262,000	3,389,000	1,914,000	24,406,000	14,255,000	5,355,000
(Loss) income before income tax expense (benefit)	(101,604,000)	1,881,000	(4,999,000)	(8,509,000)	(11,802,000)	(19,851,000)	(3,626,000)	(6,463,000)	(113,231,000)	(41,742,000)	20,029,000
Income tax expense (benefit)	(27,953,000)	946,000	3,934,000	1,353,000	1,141,000	1,976,000	1,813,000	1,842,000	(21,720,000)	6,772,000	7,809,000
Net (loss) income	$ (73,651,000)	$ 935,000	$ (8,933,000)	$ (9,862,000)	$ (12,943,000)	$ (21,827,000)	$ (5,439,000)	$ (8,305,000)	$ (91,511,000)	$ (48,514,000)	$ 12,220,000
Basic net (loss) income per share (in dollars per share)	$ (5.09)	$ 0.06	$ (0.62)	$ (0.71)	$ (1.03)	$ (1.74)	$ (0.44)	$ (0.68)	$ (6.39)	$ (3.9)	$ 1.01
Diluted net (loss) income per share (in dollars per share)	$ (5.09)	$ 0.06	$ (0.62)	$ (0.71)	$ (1.03)	$ (1.74)	$ (0.44)	$ (0.68)	$ (6.39)	$ (3.9)	$ 0.99