Product warranties (Tables)

12 Months Ended

Dec. 31, 2012

Product Warranties Disclosures [Abstract]

Provision for warranty obligations

Product warranties are as follows:

	2012			2011		2010
Balance at beginning of year	$	30,144		37,265		66,545
Warranty claims paid during the year	(55,314		)	(57,163	)	(77,017	)
Pre-existing warranty accrual adjustment during the year	—			4,473		2,261
Warranty expense during the year	58,100			45,569		45,476
Balance at end of year	$	32,930		30,144		37,265