Employee Stock Benefit Plans (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Restricted Stock Units (RSUs)	Dec. 31, 2011 Restricted Stock Units (RSUs)	Dec. 31, 2010 Restricted Stock Units (RSUs)	Dec. 31, 2012 Stock Appreciation Rights (SARs)	Dec. 31, 2011 Stock Appreciation Rights (SARs)	Dec. 31, 2012 Stock Options	Dec. 31, 2012 Performance Shares	Dec. 31, 2011 Performance Shares	Dec. 31, 2010 Performance Shares	Dec. 31, 2008 Performance Shares Performance Shares Earned in 2010	Dec. 31, 2008 Performance Shares Minimum	Dec. 31, 2008 Performance Shares Maximum	Dec. 31, 2012 Select Executives Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized for issuance as equity-based compensation		2,960,000
Stock options granted		163,042	168,939	220,007
Non-option equity awards granted					215,180	165,253	226,667	3,000	2,500		0	0	0
Award vesting period		4 years															4 years
Share-based compensation expense		$ 3,321,000	$ 5,016,000	$ 3,496,000
Non-cash compensation charges	1,700,000
Closing stock price		$ 19.35
Total unrecognized compensation expense related to nonvested stock options		1,400,000
Total fair value of shares vested during 2012		1,200,000
Award performance cycle														3 years	1 year	3 years
Exchange ratio of award shares to common stock			1
Unrecognized compensation cost related to nonvested restricted stock units granted					$ 1,600,000
Unrecognized compensation cost related to nonvested restricted stock units granted, period for recognition					1 year 10 months 24 days					2 years 7 months 6 days