Product Warranties (Details) (USD $)	3 Months Ended	6 Months Ended	12 Months Ended					3 Months Ended		6 Months Ended				12 Months Ended	3 Months Ended
	Sep. 30, 2011	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Power supply devices [Member]	Jun. 30, 2011 Power supply devices [Member]	Jun. 30, 2011 Power supply devices [Member]	Sep. 30, 2012 Power supply devices [Member]	Dec. 31, 2011 Power supply devices [Member]	Sep. 30, 2011 Power supply devices [Member]	Dec. 31, 2011 Cost of sales [Member]	Dec. 31, 2011 Accrued expenses [Member] Power supply devices [Member]	Sep. 30, 2011 Accrued expenses [Member] Power supply devices [Member]	Sep. 30, 2011 Prepaid expenses and other assets [Member]	Jun. 30, 2011 Prepaid expenses and other assets [Member]
Product Liability Contingency [Line Items]
Maximum product warranty term			3 years
Reimbursements from suppliers										$ 1,000,000				$ 1,200,000
Warranty accrual			4,455,000	6,871,000	982,000							5,500,000	2,800,000
Previously recoognized warranty liability									1,300,000
Estimated product warranty liability											1,800,000					1,500,000
Product warranty expense															2,700,000
Product warranty payments								2,000,000
Reimbursement receivable						1,200,000	1,300,000										500,000	1,300,000
Reimbursement receivable, in the form of cash and/or note receivable	500,000
Cash received pursuant to settlement		900,000
Remaining reimbursement receivable after payment			300,000
Period of product rebates/price concessions under settlement agreement			39 months
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance, beginning of period			6,871,000	982,000	993,000							5,500,000	2,800,000
Charges to operations			2,116,000	8,244,000	2,623,000
Deductions for costs incurred			(4,532,000)	(2,355,000)	(2,634,000)
Balance, end of period			$ 4,455,000	$ 6,871,000	$ 982,000							$ 5,500,000	$ 2,800,000