Business and Summary of Significant Accounting Principles (Cash Flow Statements Immaterial Error Correction) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income	$ 3,523	$ 7,239	$ 8,580	$ 6,594
Depreciation and amortization expense	32,120	30,653	97,850	93,298
Income tax expense	(5,270)	(7,979)	(10,387)	(7,303)
Scenario As Previously Reported [Member]
Net income		7,210		6,738
Depreciation and amortization expense		30,702		93,054
Income tax expense		7,959		7,403
Adjustment [Member]
Net income		29		(144)
Depreciation and amortization expense		(49)		244
Income tax expense		$ 20		$ (100)