Earnings Per Share Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Shares used in the denominators of the basic and diluted earnings per share computations
Shares for basic per share computation - weighted average common shares outstanding	49,374	49,032
Dilutive effect of common stock equivalents	815	810
Shares for diluted per share computation	50,189	49,842
Options and stock appreciation rights ("SARs") excluded from computation as anti-dilutive because they are out-of-the-money	1,581	1,457
Unvested restricted stock and restricted stock units ("RSUs") considered to be participating securities	253	219
Effect (decrease) of allocation of undistributed earnings (net income) to the participating securities under the two class method:
Basic earnings per share	$ 0	$ 0
Diluted earnings per share	$ 0	$ 0