Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Compensation and Retirement Disclosure [Abstract]
Officer cash bonus target minimum	30.00%
Officer cash bonus target maximum	130.00%
Officer cash bonus performance factor minimum	0.00%
Officer cash bonus performance factor maximum	200.00%
Other management cash bonus target minimum	10.00%
Other management cash bonus target maximum	30.00%
Number of outstanding options and warrants	889,382		1,144,309
Possible future share issuance authorized under equity incentive plan	1,742,237		2,047,550
Total shares reserved for future issuance	2,631,619		3,191,859
Possible future share issuance authorized under equity incentive plan restricted stock	400,000
Possible future share issuance authorized under charter	110,100,000
Stock-based compensation expense	$ 6,899,000		$ 7,613,000		$ 6,094,000
Total unrecognized stock-based compensation costs	4,000,000
Weighted average remaining term of vesting periods (in years)	2 years 4 months
401(k) Savings Plan [Abstract]
401(k) employer match percentage	75.00%
401(k) employer match salary limit percentage	6.00%
401(k) employer contribution	1,100,000		1,000,000		1,100,000
Retirement Plan [Abstract]
Retirement plan qualification years of service (in years)	30 years
Retirement plan qualification age	55 years
Retirement plan qualification minimum years of service (in years)	10 years
2009 and prior retirement plan immediate vesting percentage	100.00%
Deferred Compensation [Abstract]
Marketable securities of non-qualified deferred compensation plan fair value disclosure	3,996,000		3,354,000		3,149,000
Non Qualified Deferred Compensation Obligation Fair Value Disclosure [Roll Forward]
Beginning deferred compensation liability	3,354,000		3,149,000		4,091,000
Contributions to deferred compensation plans	0		0		545,000
Mark to market adjustment to deferred compensation (in general and administrative expenses)	803,000		475,000		(119,000)
Distributions from deferred compensation plans	(161,000)		(270,000)		(1,368,000)
Ending deferred compensation liability	3,996,000		3,354,000		3,149,000
Employee Stock Purchase Plan [Abstract]
Employee stock purchase plan salary limit percentage	25.00%
Employee stock purchase plan market percentage	85.00%
Number of days at end of quarter used to calculate ESPP discount	5 days
Shares of Common Stock issued under the employee stock purchase plans	27,250		34,126		30,826
Discount on newly issued shares expensed as additional compensation	200,000		200,000		200,000
Stock Options [Member]
Stock Option Activity Rollforward [Abstract]
Balance of options outstanding	1,129,309	[1],[2]	1,209,455		1,480,196
Options granted	168,700		190,886		146,581
Options exercised	(423,627)		(271,032)		(417,322)
Balance of options outstanding	874,382		1,129,309	[1],[2]	1,209,455
Options outstanding, weighted average exercise price	$ 30.10	[1],[2]	$ 29.08		$ 27.95
Options granted, weighted average exercise price	$ 36.50		$ 31.97		$ 33.93
Options exercised, weighted average exercise price	$ 28.22		$ 26.87		$ 26.79
Options outstanding, weighted average exercise price	$ 32.24		$ 30.10	[1],[2]	$ 29.08
Weighted average remaining life of outstanding options	3 years 5 months
Options exercisable	441,507
Weighted average exercise price	$ 30.77
Weighted average remaining life	1 year 7 months 10 days
Intrinsic value	3,200,000
Amount of exercisable options with prices higher than the market price of Company Common Stock	134,628
Cash received or receivable from options exercised	12,500,000		7,400,000		11,900,000
Total instrinsic value of options exercised	3,900,000		1,900,000		3,000,000
Total intrinsic value of options outstanding	4,300,000		5,000,000		3,300,000
Prior to 2005 Stock Options [Member]
Compensation and Retirement Disclosure [Abstract]
Vesting term of stock options issued (in years)	4 years
Option expiration period (in years)	10 years
Stock Option Activity Rollforward [Abstract]
Period for absolute total return (in years)	4 years
2005 and Subsequent Stock Options [Member]
Compensation and Retirement Disclosure [Abstract]
Vesting term of stock options issued (in years)	4 years
Option expiration period (in years)	7 years
Grant date fair value of each stock option granted (in dollars per option)	$ 6.50		$ 5.47		$ 6.47
Assumptions Used in Determining Fair Values of Options Granted:
Risk free interest rate	1.00%	[3]	1.10%	[3]	2.40%	[3]
Common stock dividend yield	4.70%	[4]	5.30%	[4]	5.00%	[4]
Expected volatility rate	32.40%	[5]	33.40%	[5]	32.50%	[5]
Average expected option life (in years)	5 years 9 months	[6]	5 years 9 months	[6]	5 years 9 months	[6]
Dividends paid for previous year	1 year
Stock Option Activity Rollforward [Abstract]
Period for absolute total return (in years)	4 years
Time-Based Restricted Stock [Member]
Stock Option Activity Rollforward [Abstract]
Percentage of employees restricted stock vested per anniversary date	25.00%
Percentage of directors time-based restricted stock that vest each year after grant date	25.00%
Grant date fair value of restricted stock	$ 36.64	[7]	$ 32.27	[7]	$ 33.70	[7]
Restricted Stock Activity Rollforward [Abstract]
Balance of restricted stock outstanding	222,502		224,661		264,326
Awarded and issued	86,144	[7]	90,983	[7]	76,966	[7]
Vested	(94,037)	[8]	(92,239)	[8]	(116,631)	[8]
Forfeited	(1,813)		(903)		0
Balance of restricted stock outstanding	212,796		222,502		224,661
Restricted stock outstanding, weighted average grant date fair value	$ 30.31		$ 28.02		$ 27.08
Awarded and issued, weighted average grant date fair value	$ 36.64	[7]	$ 32.27	[7]	$ 33.70	[7]
Vested, weighted average grant date fair value	$ 27.80	[8]	$ 27.14	[8]	$ 30.64	[8]
Forfeited, weighted average grant date fair value	$ 36.01		$ 30.12		$ 0.00
Restricted stock outstanding, weighted average grant date fair value	$ 33.96		$ 30.31		$ 28.02
Fair value at grant date of restricted stock issued	3,200,000		2,900,000		2,600,000
Vesting date fair value of restricted stock	3,400,000		2,900,000		3,900,000
Total Return-Based Restricted Stock [Member]
Compensation and Retirement Disclosure [Abstract]
Vesting term of stock options issued (in years)	3 years
Assumptions Used in Determining Fair Values of Options Granted:
Risk free interest rate	0.40%	[9]	0.40%	[9]	1.00%	[9]
Common stock dividend yield	4.90%	[10]	5.40%	[10]	5.40%	[10]
Expected volatility rate	43.40%	[11]	43.70%	[11]	42.80%	[11]
Dividends paid for previous year	1 year
Period preceding date of grant	0 years 3 months
Stock Option Activity Rollforward [Abstract]
Percentage of return-based restricted stock issued to officers that will vest, minimum	0.00%		0.00%		0.00%
Percentage of return-based restricted stock issued to officers that will vest, maximum	150.00%		250.00%		250.00%
Period for absolute total return (in years)	3 years
Grant date fair value of restricted stock	$ 31.73	[12]	$ 38.71	[12]	$ 41.02	[12]
Restricted Stock Activity Rollforward [Abstract]
Balance of restricted stock outstanding	125,288		122,829		231,835
Awarded and issued	65,486	[12]	67,902	[12]	57,386	[12]
Vested	(41,863)	[13]	(32,722)	[13]	(66,417)	[13]
Forfeited	(15,523)		(32,721)		(99,975)
Balance of restricted stock outstanding	133,388		125,288		122,829
Restricted stock outstanding, weighted average grant date fair value	$ 32.87		$ 34.86		$ 21.03
Awarded and issued, weighted average grant date fair value	$ 31.73	[12]	$ 38.71	[12]	$ 41.02	[12]
Vested, weighted average grant date fair value	$ 24.75	[13]	$ 29.47	[13]	$ 13.79	[13]
Forfeited, weighted average grant date fair value	$ 24.75		$ 29.47		$ 13.79
Restricted stock outstanding, weighted average grant date fair value	$ 35.29		$ 32.87		$ 34.86
Fair value at grant date of restricted stock issued	2,100,000		2,600,000		2,400,000
Vesting date fair value of restricted stock	$ 1,500,000		$ 1,100,000		$ 2,000,000

[1] The outstanding options at December 31, 2013 had a weighted average remaining life of 3.4 years.

[2] The Company had 441,507 options exercisable at December 31, 2013 with a weighted average exercise price of $30.77, weighted average remaining life of 1.6 years and intrinsic value of $3.2 million. Of these exercisable options, 134,628 had exercise prices higher than the market price of our Common Stock at December 31, 2013.

[3] Represents the interest rate as of the grant date on US treasury bonds having the same life as the estimated life of the option grants.

[4] The dividend yield is calculated utilizing the dividends paid for the previous one-year period and the per share price of Common Stock on the date of grant.

[5] Based on the historical volatility of Common Stock over a period relevant to the related stock option grant.

[6] The average expected option life is based on an analysis of the Company's historical data.

[7] The fair value at grant date of time-based restricted stock issued during the years ended December 31, 2013, 2012 and 2011 was $3.2 million, $2.9 million and $2.6 million, respectively.

[8] The vesting date fair value of time-based restricted stock that vested during the years ended December 31, 2013, 2012 and 2011 was $3.4 million, $2.9 million and $3.9 million, respectively. Vested shares include those shares surrendered by employees to satisfy tax withholding obligations in connection with such vesting.

[9] Represents the interest rate as of the grant date on US treasury bonds having the same life as the estimated life of the total return-based restricted stock grants.

[10] The dividend yield is calculated utilizing the dividends paid for the previous one-year period and the average per share price of Common Stock during the three-month period preceding the date of grant.

[11] Based on the historical volatility of Common Stock over a period relevant to the related total return-based restricted stock grant.

[12] The fair value at grant date of total return-based restricted stock issued during the years ended December 31, 2013, 2012 and 2011 was $2.1 million, $2.6 million and $2.4 million, respectively.

[13] The vesting date fair value of total return-based restricted stock that vested during the years ended December 31, 2013, 2012 and 2011 was $1.5 million, $1.1 million and $2.0 million, respectively. Vested shares include those shares surrendered by employees to satisfy tax withholding obligations in connection with such vesting.