Accounts Receivable (Schedule Of Accounts Receivable) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	$ 345,174	$ 330,120
Less: Allowance for doubtful accounts	6,450	6,085	6,614	549
Accounts receivable, net	338,724	324,035
Trade Customers [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	324,917	308,552
Equipment Manufacturers [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	5,443	6,334
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	$ 14,814	$ 15,234