Stock Based Compensation (Textual) (Details) (USD $)	12 Months Ended						12 Months Ended						1 Months Ended	12 Months Ended					0 Months Ended	1 Months Ended	12 Months Ended						12 Months Ended			3 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended							1 Months Ended		12 Months Ended			1 Months Ended		12 Months Ended	1 Months Ended		12 Months Ended		1 Months Ended						0 Months Ended	1 Months Ended		12 Months Ended			1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended					0 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended			1 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended				12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Stock Incentive Plan 2004	Dec. 31, 2012 Stock Incentive Plan 2004	Dec. 31, 2011 Stock Incentive Plan 2004	Dec. 31, 2013 Stock Incentive Plan 2004 Maximum	Dec. 31, 2013 Director Restricted Stock Plan	Dec. 31, 2012 Director Restricted Stock Plan	Dec. 31, 2011 Director Restricted Stock Plan	Dec. 31, 2013 Director Restricted Stock Plan Annual Grant	Dec. 31, 2012 Director Restricted Stock Plan Annual Grant	Dec. 31, 2011 Director Restricted Stock Plan Annual Grant	Aug. 02, 2011 Key Management 2002 Restricted Stock Plan	Dec. 31, 2013 Key Management 2002 Restricted Stock Plan	Dec. 31, 2012 Key Management 2002 Restricted Stock Plan	Dec. 31, 2011 Key Management 2002 Restricted Stock Plan	Dec. 31, 2002 Key Management 2002 Restricted Stock Plan	Dec. 31, 2013 Stock Incentive Plan 2013 Maximum	Mar. 23, 2010 Executive 2010 Restricted Stock	Mar. 23, 2010 Executive 2010 Restricted Stock	Dec. 31, 2013 Executive 2010 Restricted Stock	Dec. 31, 2012 Executive 2010 Restricted Stock	Dec. 31, 2011 Executive 2010 Restricted Stock	Dec. 31, 2013 Stock Options	Dec. 31, 2010 Stock Options	Dec. 31, 2013 Stock Option And Incentive Plan 1994 Maximum	Dec. 31, 2013 Employee Stock Purchase Plan	Dec. 31, 2012 Employee Stock Purchase Plan	Dec. 31, 2011 Employee Stock Purchase Plan	Dec. 31, 2012 Key Management Twenty Twelve Restricted Stock Plan	Dec. 31, 2013 Key Management Twenty Twelve Restricted Stock Plan	Dec. 31, 2012 Key Management Twenty Twelve Restricted Stock Plan	Dec. 31, 2013 Key Management Twenty Twelve Restricted Stock Plan One Year from Balance Sheet Date	Dec. 31, 2013 Key Management Twenty Twelve Restricted Stock Plan One Year from Balance Sheet Date	Dec. 31, 2012 Key Management Twenty Twelve Restricted Stock Plan One Year from Balance Sheet Date	Dec. 31, 2013 Key Management Twenty Twelve Restricted Stock Plan More than One and within Two Years from Balance Sheet Date	Dec. 31, 2012 Key Management Twenty Twelve Restricted Stock Plan More than One and within Two Years from Balance Sheet Date	Dec. 31, 2013 Key Management Twenty Twelve Restricted Stock Plan Three Months	Dec. 31, 2012 Key Management Twenty Twelve Restricted Stock Plan Three Months	Dec. 31, 2013 Key Management Twenty Twelve Restricted Stock Plan Market Based Restricted Stock	Aug. 02, 2011 Key Management Twenty Eleven Restricted Stock Person	Jan. 03, 2011 Key Management Twenty Eleven Restricted Stock	Dec. 31, 2013 Key Management Twenty Eleven Restricted Stock	Dec. 31, 2012 Key Management Twenty Eleven Restricted Stock	Dec. 31, 2013 Key Management Twenty Eleven Restricted Stock Three-year Program	Aug. 02, 2011 Key Management Twenty Eleven Restricted Stock One Year from Balance Sheet Date	Jan. 03, 2011 Key Management Twenty Eleven Restricted Stock One Year from Balance Sheet Date	Dec. 31, 2013 Key Management Twenty Eleven Restricted Stock One Year from Balance Sheet Date	Aug. 02, 2011 Key Management Twenty Eleven Restricted Stock Three Months	Jan. 03, 2011 Key Management Twenty Eleven Restricted Stock Three Months	Dec. 31, 2013 Key Management Twenty Eleven Restricted Stock Three Months	Dec. 31, 2013 Key Management Twenty Eleven Restricted Stock Market Based Restricted Stock	Aug. 02, 2011 Key Management Twenty Eleven Restricted Stock For 0.50 years	Jan. 03, 2011 Key Management Twenty Eleven Restricted Stock For 0.50 years	Aug. 02, 2011 Key Management Twenty Eleven Restricted Stock Nine Months	Jan. 03, 2011 Key Management Twenty Eleven Restricted Stock Nine Months	Aug. 02, 2011 Key Management Twenty Eleven Restricted Stock Performance Based Awards	Jan. 03, 2011 Key Management Twenty Eleven Restricted Stock Performance Based Awards	Aug. 02, 2011 Key Management 2010 Restricted Stock	Aug. 02, 2011 Key Management 2010 Restricted Stock	Mar. 23, 2010 Key Management 2010 Restricted Stock	Dec. 31, 2013 Key Management 2010 Restricted Stock	Dec. 31, 2012 Key Management 2010 Restricted Stock	Dec. 31, 2011 Key Management 2010 Restricted Stock	Mar. 23, 2010 Key Management 2010 Restricted Stock One Year from Balance Sheet Date	Dec. 31, 2013 Key Management 2010 Restricted Stock One Year from Balance Sheet Date	Dec. 31, 2013 Key Management 2010 Restricted Stock Service Based Awards	Mar. 23, 2010 Key Management 2010 Restricted Stock Service Based Awards	Mar. 23, 2010 Key Management 2010 Restricted Stock Three Months	Jan. 31, 2011 Key Management 2010 Restricted Stock Market Based Restricted Stock	Dec. 31, 2013 Key Management 2010 Restricted Stock For 0.50 years	Dec. 31, 2013 Key Management 2010 Restricted Stock Nine Months	Dec. 31, 2013 Key Management 2010 Restricted Stock Maximum Three-year Program	Dec. 31, 2013 Key Management 2010 Restricted Stock Minimum Three-year Program	Aug. 02, 2011 Key Management 2008 Restricted Stock	Aug. 02, 2011 Key Management 2008 Restricted Stock	Sep. 30, 2008 Key Management 2008 Restricted Stock	Dec. 31, 2013 Key Management 2008 Restricted Stock	Dec. 31, 2012 Key Management 2008 Restricted Stock	Dec. 31, 2011 Key Management 2008 Restricted Stock	Jan. 03, 2012 Key Management 2008 Restricted Stock Three-year Program	Sep. 30, 2008 Key Management 2008 Restricted Stock Three-year Program	Dec. 31, 2013 Key Management 2008 Restricted Stock Three-year Program	Sep. 30, 2008 Key Management 2008 Restricted Stock One Year from Balance Sheet Date	Sep. 30, 2008 Key Management 2008 Restricted Stock More than One and within Two Years from Balance Sheet Date	Sep. 30, 2008 Key Management 2008 Restricted Stock Service Based Awards	Sep. 30, 2008 Key Management 2008 Restricted Stock Three Months	Dec. 31, 2013 Key Management 2008 Restricted Stock Three Months	Sep. 30, 2008 Key Management 2008 Restricted Stock For 4.00 years	Dec. 31, 2013 Key Management 2008 Restricted Stock For 4.00 years	Sep. 30, 2008 Key Management 2008 Restricted Stock More than Two and within Three Years from Balance Sheet Date	Sep. 30, 2008 Key Management 2008 Restricted Stock More than Three and within Four Years from Balance Sheet Date	Sep. 30, 2008 Key Management 2008 Restricted Stock Market Based Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock and stock option granted under the plan (shares)																										2,400,000.0
Restricted stock and stock option to be granted under the plan (shares)						500,000												225,000
Total compensation costs			$ 2,653,000	$ 2,214,000	$ 5,522,000																						$ 66,000	$ 46,000	$ 59,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized			4,158,000				263,000							0							0										1,203,000												0																			0																83,000
Employee Service Share Based Compensation Unrecognized Compensation Costs Nonvested Awards Weighted Average Period Of Recognition			1 year 2 months				2 months 12 days																								1 year 4 months 2 days																																															10 months 10 days
Total cash paid for settlement of plan shares			354,000	995,000	1,604,000
Shares authorized for issuance under employee stock purchase plan (shares)																											150,000
Maximum number of shares that can be purchased under employee stock purchase plan (shares)																											15,000
Common stock price as percentage of the market price (percent)																											85.00%
Shares purchased under employee stock purchase plan (shares)																											6,865	6,019	5,732
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period														5 years										5 years									1 year	1 year		2 years		3 months							3 months	1 year		1 year			3 months																						1 year	3 months									3 years					3 months		4 years
Shares Recategorized from Liabilities to Equity													7,316																																															18,720				1,689,000												6,374
Percentage option vested in year one (percent)																								10.00%
Percentage option vested in year two (percent)																								10.00%
Percentage option vested in year three (percent)																								20.00%
Percentage option vested in year four (percent)																								30.00%
Percentage option in year five (percent)																								30.00%
Expiration period (years)																								10 years
Options granted (shares)	0
Exercised (shares)	0
Total intrinsic value of option exercised																									407,000
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period																	97,881			2,710																																																18,171		37,002											17,343					15,920
Restricted stock fair values at the grant date (dollars per share)	$ 0	$ 0					$ 69.08						$ 69.37				$ 25.65		$ 54.38		$ 0.00									$ 62.55	$ 62.55										$ 69.37	$ 63.96	$ 0.00																$ 69.37																$ 69.37			$ 0.00
Share Based Compensation Arrangement By Share Based Payment Award Vesting Percentage														20.00%																										25.00%												50.00%										50.00%																					25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value							360,000	200,000	200,000					0	740,000	702,000					34,000	64,000	49,000								35,000												752,000	930,000																			1,733,000															346,000	650,000	230,000
Stock incentive nonemployee directors restricted share units granted, value										$ 60,000	$ 60,000	$ 50,000
Requisite service period to receive grants in restricted shares of common stock (years)							1 year
Restricted common stock vesting rights description																																																																														0
Shares vest beginning date																				Mar. 23, 2011																				Jan. 10, 2014												Mar. 01, 2012																															Jan. 01, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate																																			0.17%				0.00%							0.16%	0.28%		0.06%	0.13%															0.41%				0.14%																		1.95%		3.24%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate																																4.19%									3.618%	3.92%																			4.52%																4.669%
Options granted, fair value per share (dollars per share)																																									$ 69.37		$ 63.96																		$ 54.38																$ 52.69
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate																																			31.17%		29.65%									18.71%	23.46%						18.47%	22.56%	18.16%	24.14%										35.65%					24.12%	27.14%												34.87%	30.92%						29.63%	28.61%
Volatilities for peers, minimum																																																																													25.05%
Volatilities for peers, maximum																																																																													49.94%
Expected life in years																																																									1 year 7 months	2 years 2 months								1 year	1 year 9 months 14 days				6 months	9 months										7 years 6 months				5 years 6 months							2 years 6 months
Issued (shares)							6,510														0										16,593									16,593			0									25,355																										0
Restricted stock plan modification, number of participants																																									52
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period							5,340														634										565												10,938																				0															5,851