Stock-Based Compensation (Restricted Stock) (Details) (USD $)	12 Months Ended				0 Months Ended													1 Months Ended		12 Months Ended																																									0 Months Ended					12 Months Ended
	Dec. 31, 2012 Restricted stock units	Dec. 31, 2011 Restricted stock units	Dec. 31, 2010 Restricted stock units	Dec. 31, 2012 1995 Executive Incentive Compensation Plan	Nov. 16, 2012 1995 Executive Incentive Compensation Plan Restricted stock units	Sep. 10, 2012 1995 Executive Incentive Compensation Plan Restricted stock units	May 04, 2012 1995 Executive Incentive Compensation Plan Restricted stock units	Mar. 16, 2012 1995 Executive Incentive Compensation Plan Restricted stock units	Jan. 23, 2012 1995 Executive Incentive Compensation Plan Restricted stock units	Sep. 20, 2011 1995 Executive Incentive Compensation Plan Restricted stock units	Apr. 26, 2011 1995 Executive Incentive Compensation Plan Restricted stock units	Sep. 22, 2010 1995 Executive Incentive Compensation Plan Restricted stock units	Jan. 25, 2010 1995 Executive Incentive Compensation Plan Restricted stock units	Nov. 19, 2009 1995 Executive Incentive Compensation Plan Restricted stock units	Jan. 27, 2009 1995 Executive Incentive Compensation Plan Restricted stock units	Jan. 22, 2008 1995 Executive Incentive Compensation Plan Restricted stock units	Jan. 23, 2007 1995 Executive Incentive Compensation Plan Restricted stock units	May 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units	Mar. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units January 23, 2007	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units January 23, 2007	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units January 23, 2007	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units January 22, 2008	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units January 22, 2008	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units January 22, 2008	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units January 27, 2009	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units January 27, 2009	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units January 27, 2009	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units November 19, 2009	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units November 19, 2009	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units November 19, 2009	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units January 25, 2010	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units January 25, 2010	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units January 25, 2010	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units September 22, 2010	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units September 22, 2010	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units September 22, 2010	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units April 26, 2011	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units April 26, 2011	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units April 26, 2011	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units September 20, 2011	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units September 20, 2011	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units September 20, 2011	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units January 23, 2012	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units January 23, 2012	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units January 23, 2012	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units March 16, 2012	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units March 16, 2012	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units March 16, 2012	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units May 4, 2012	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units May 4, 2012	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units May 4, 2012	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units September 10, 2012	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units September 10, 2012	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units September 10, 2012	Dec. 31, 2012 1995 Executive Incentive Compensation Plan Restricted stock units November 16, 2012	Dec. 31, 2011 1995 Executive Incentive Compensation Plan Restricted stock units November 16, 2012	Dec. 31, 2010 1995 Executive Incentive Compensation Plan Restricted stock units November 16, 2012	Dec. 31, 2012 1995 Non-Employee Directors' Stock Plan	Dec. 04, 2012 1995 Non-Employee Directors' Stock Plan Restricted stock units	May 02, 2012 1995 Non-Employee Directors' Stock Plan Restricted stock units	May 02, 2011 1995 Non-Employee Directors' Stock Plan Restricted stock units	May 03, 2010 1995 Non-Employee Directors' Stock Plan Restricted stock units	May 01, 2009 1995 Non-Employee Directors' Stock Plan Restricted stock units	Dec. 31, 2012 1995 Non-Employee Directors' Stock Plan Restricted stock units	Dec. 31, 2012 1995 Non-Employee Directors' Stock Plan Restricted stock units May 1, 2009	Dec. 31, 2011 1995 Non-Employee Directors' Stock Plan Restricted stock units May 1, 2009	Dec. 31, 2010 1995 Non-Employee Directors' Stock Plan Restricted stock units May 1, 2009	Dec. 31, 2012 1995 Non-Employee Directors' Stock Plan Restricted stock units May 3, 2010	Dec. 31, 2011 1995 Non-Employee Directors' Stock Plan Restricted stock units May 3, 2010	Dec. 31, 2010 1995 Non-Employee Directors' Stock Plan Restricted stock units May 3, 2010	Dec. 31, 2012 1995 Non-Employee Directors' Stock Plan Restricted stock units May 2, 2011	Dec. 31, 2011 1995 Non-Employee Directors' Stock Plan Restricted stock units May 2, 2011	Dec. 31, 2010 1995 Non-Employee Directors' Stock Plan Restricted stock units May 2, 2011	Dec. 31, 2012 1995 Non-Employee Directors' Stock Plan Restricted stock units May 2, 2012	Dec. 31, 2011 1995 Non-Employee Directors' Stock Plan Restricted stock units May 2, 2012	Dec. 31, 2010 1995 Non-Employee Directors' Stock Plan Restricted stock units May 2, 2012	Dec. 31, 2012 1995 Non-Employee Directors' Stock Plan Restricted stock units December 4, 2012	Dec. 31, 2011 1995 Non-Employee Directors' Stock Plan Restricted stock units December 4, 2012	Dec. 31, 2010 1995 Non-Employee Directors' Stock Plan Restricted stock units December 4, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares authorized for issuance				8,000,000																																																								600,000
Number of shares available for grant				1,165,744																																																								186,190
Vesting period (in years)																		3 years	3 years	3 years																																														1 year
Retirement age of employees (in years)																		62 years	62 years	62 years
Granted (in shares)	172,104	37,442	42,000		5,000	5,985	56,233	44,268	30,000	13,500	3,750	25,000	1,000	15,000	106,625	130,950	101,700																																												2,688	27,930	20,192	16,000	16,000
Granted (in dollars per share)	$ 19.23	$ 29.61	$ 26.53		$ 16.45	$ 19.05	$ 17.34	$ 21.39	$ 17.81	$ 21.18	$ 32.10	$ 23.47	$ 31.49	$ 31.90	$ 25.15	$ 45.95	$ 38.25																																												$ 19.95	$ 21.58	$ 34.79	$ 30.99	$ 27.28
Expense (Income)	$ 1,420,000	$ 1,850,000	$ 3,297,000																		$ 0	$ 0	$ 41,000	$ 0	$ 68,000	$ 1,601,000	$ 43,000	$ 614,000	$ 667,000	$ 0	$ 12,000	$ 298,000	$ 1,000	$ 10,000	$ 20,000	$ 20,000	$ 373,000	$ 194,000	$ 44,000	$ 29,000	$ 0	$ 151,000	$ 111,000	$ 0	$ 168,000	$ 0	$ 0	$ 130,000	$ 0	$ 0	$ 213,000	$ 0	$ 0	$ 11,000	$ 0	$ 0	$ 3,000	$ 0	$ 0								$ 0	$ 0	$ 145,000	$ 0	$ 165,000	$ 331,000	$ 234,000	$ 468,000	$ 0	$ 402,000	$ 0	$ 0	$ 0	$ 0	$ 0
Restricted stock unit activity
Nonvested at the beginning of the period (in shares)	62,641	140,535	229,491
Granted (in shares)	172,104	37,442	42,000		5,000	5,985	56,233	44,268	30,000	13,500	3,750	25,000	1,000	15,000	106,625	130,950	101,700																																												2,688	27,930	20,192	16,000	16,000
Vested restricted Stock Units (in shares)	(67,861)	(113,136)	(124,424)
Forfeited (in shares)	(25,411)	(2,200)	(6,532)
Nonvested at the end of the period (in shares)	141,473	62,641	140,535
Weighted Average Grant-Date Fair Value
Nonvested at the beginning of the period (in dollars per share)	$ 25.39	$ 30.83	$ 34.45
Granted (in dollars per share)	$ 19.23	$ 29.61	$ 26.53		$ 16.45	$ 19.05	$ 17.34	$ 21.39	$ 17.81	$ 21.18	$ 32.10	$ 23.47	$ 31.49	$ 31.90	$ 25.15	$ 45.95	$ 38.25																																												$ 19.95	$ 21.58	$ 34.79	$ 30.99	$ 27.28
Vested (in dollars per share)	$ 24.86	$ 33.55	$ 35.81
Forfeited (in dollars per share)	$ 20.35	$ 25.15	$ 35.23
Nonvested at the end of the period (in dollars per share)	$ 19.19	$ 25.39	$ 30.83
Additional disclosures
Unrecognized stock-based compensation expense	$ 1,900,000
Unrecognized stock-based compensation expense, period of recognition	2 years