Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012
Consolidated Balance Sheets
Trade accounts receivable, allowance for doubtful accounts (in dollars)	$ 2,945	$ 2,583
Property and equipment, accumulated depreciation (in dollars)	366,139	352,164
Intangible assets, excluding goodwill, accumulated amortization (in dollars)	$ 68,364	$ 59,192
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, Authorized shares	500,000	500,000
Common stock, shares issued	167,756	180,548
Common stock, shares outstanding	167,424	180,241
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, Authorized shares	50,000	50,000
Preferred stock, shares issued	0	0