Accounts Receivable, Net of Allowance (Schedule of Allowance for Doubtful Accounts) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for Doubtful Accounts Receivable [Roll Forward]
Allowance for doubtful accounts at beginning of year	$ 7,600,000	$ 8,300,000
Provision for doubtful accounts	6,970,000	2,016,000	2,895,000
Amounts charged against the allowance	(3,300,000)	(2,700,000)
Allowance for doubtful accounts at end of year	11,200,000	7,600,000	8,300,000
Segment, Continuing Operations [Member]
Allowance for Doubtful Accounts Receivable [Roll Forward]
Provision for doubtful accounts	$ 6,900,000	$ 2,000,000