Stock-Based Compensation, Common Stock Repurchases and Dividends Schedule Of Share-Based Payment Arrangements (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost charged against income, before income tax benefit	$ 2,124	$ 1,981	$ 1,937
Stock-based compensation cost included in:
Cost of revenues	137	124	128
Operating expenses	1,987	1,857	1,809
Income tax benefit related to stock-based compensation included in net income	0	(692)	(668)
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost charged against income, before income tax benefit	1,387	1,447	1,467
Restricted stock and restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost charged against income, before income tax benefit	$ 737	$ 534	$ 470