Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Current assets:
Allowance for uncollectible accounts	$ 4,844	$ 4,067
Shareholders' equity:
Common stock, shares authorized	240,000
Common stock, shares issued	105,333	105,530