Income Taxes - Deferred Tax Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Accrued expenses	$ 43,622	$ 39,881
Warranty accrual	26,296	18,386
Deferred compensation	18,587	18,659
Allowance for doubtful accounts	9,239	7,189
Inventory	11,490	11,610
Deferred revenue	15,361	14,669
Pension and postretirement benefits	66,222	54,990
Finance lease receivables	6,210	0
Tax credits	23,738	46,330
Net operating loss carryforwards	74,528	86,918
Capital loss carryforwards	3,534	3,604
Deferred Tax Assets, State Taxes	17,341	13,061
Other	7,083	7,961
Deferred Tax Assets, Gross	323,251	323,258
Valuation allowance	(57,303)	(66,988)
Net deferred tax assets	265,948	256,270
Deferred tax liabilities:
Property, plant and equipment	14,369	20,116
Goodwill	41,175	36,712
Finance lease receivables	0	3,655
Investment in partnership	17,056	18,372
Undistributed earnings	5,016	4,750
Other	3,511	3,867
Net deferred tax liabilities	81,127	87,472
Net deferred tax asset	$ 184,821	$ 168,798