Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
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	1,224,455		1,495,196
Possible future share issuance authorized under equity incentive plan	2,363,695		2,642,620
Total shares reserved for future issuance	3,588,150		4,137,816
Possible future share issuance authorized under equity incentive plan restricted stock	700,000
Possible future share issuance authorized under charter	127,400,000
Stock-based compensation expense	$ 6,094,000		$ 6,572,000		$ 6,567,000
Total unrecognized stock-based compensation costs	5,600,000
Weighted average remaining contractual term for recognition of unrecognized stock-based compensation costs (in years)	2.1
Retirement Plan [Abstract]
Retirement plan qualification years of service (in years)	30
Retirement plan qualification age	55
Retirement plan qualification minimum years of service (in years)	10
2009 and prior retirement plan immediate vesting percentage	100.00%
Deferred Compensation [Abstract]
Marketable securities of non-qualified deferred compensation plan fair value disclosure	3,149,000		3,479,000		6,100,000
Non Qualified Deferred Compensation Obligation Fair Value Disclosure [Roll Forward]
Beginning deferred compensation liability	4,091,000		6,898,000		6,522,000
Contributions to deferred compensation plans	545,000		229,000		0
Mark to market adjustment to deferred compensation	(119,000)		246,000		1,497,000
Distributions from deferred compensation plans	(1,368,000)		(3,282,000)		(1,121,000)
Ending deferred compensation liability	3,149,000		4,091,000		6,898,000
Units of phantom stock discount	15.00%
Phantom stock dividend discount	15.00%
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		1,000,000
Employee Stock Purchase Plan [Abstract]
Employee stock purchase plan salary limit percentage	25.00%
Employee stock purchase plan market percentage	85.00%
Employee stock purchase plan average market price percentage	85.00%
Number of days at beginning of quarter used to calculate ESPP discount	5
Number of days at end of quarter used to calculate ESPP discount	5
Shares of Common Stock issued under the employee stock purchase plans	30,826		27,378		37,287
Discount on newly issued shares expensed as additional compensation	200,000		100,000		300,000
Stock Options [Member]
Stock Option Activity Rollforward [Abstract]
Balance of options outstanding	1,480,196	[1],[2]	1,467,773		1,489,250
Options granted	146,581		190,826		394,044
Options cancelled	0				(111,590)
Options exercised	(417,322)		(178,403)		(303,931)
Balance of options outstanding	1,209,455		1,480,196	[1],[2]	1,467,773
Options outstanding, weighted average exercise price	$ 27.95	[1],[2]	$ 27.15		$ 28.74
Options granted, weighted average exercise price	$ 33.93		$ 29.05		$ 19.00
Options cancelled, weighted average exercise price	$ 0.00				$ 27.65
Options exercised, weighted average exercise price	$ 26.79		$ 22.54		$ 24.18
Options outstanding, weighted average exercise price	$ 29.08		$ 27.95	[1],[2]	$ 27.15
Weighted average remaining life of outstanding options	3.5
Options exercisable	646,029
Weighted average exercise price	$ 31.01
Weighted average remaining life	2.4
Intrinsic value	1,100,000
Amount of exercisable options with prices higher than the market price of Company Common Stock	252,277
Cash received or receivable from options exercised	11,900,000		4,400,000		7,400,000
Total instrinsic value of options exercised	3,000,000		1,700,000		2,000,000
Total intrinsic value of options outstanding	3,300,000		7,200,000		10,300,000
Prior to 2005 Stock Options [Member]
Compensation and Retirement Disclosure [Abstract]
Vesting period of stock options issued (in years)	4
Option expiration period (in years)	10
Stock Option Activity Rollforward [Abstract]
Period for absolute total return (in years)	4
2005 and Subsequent Stock Options [Member]
Compensation and Retirement Disclosure [Abstract]
Vesting period of stock options issued (in years)	4
Option expiration period (in years)	7
Weighted average grant date fair value of each stock option granted (in dollars per option)	$ 6.47		$ 4.96		$ 1.82
Assumptions Used in Determining Fair Values of Options Granted:
Risk free interest rate	2.40%	[3]	2.60%	[3]	2.30%	[3]
Common stock dividend yield	5.00%	[4]	5.90%	[4]	9.00%	[4]
Expected volatility rate	32.50%	[5]	32.20%	[5]	29.90%	[5]
Average expected option life (in years)	5.75	[6]	5.75	[6]	5.75	[6]
Dividends paid for previous year	1
Stock Option Activity Rollforward [Abstract]
Period for absolute total return (in years)	4
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%
Restricted Stock Activity Rollforward [Abstract]
Balance of restricted stock outstanding	264,326		316,074		329,795
Awarded and issued	76,966	[7]	88,930	[7]	128,384	[7]
Vested	(116,631)	[8]	(138,745)	[8]	(132,779)	[8]
Forfeited	0		(1,933)		(9,326)
Balance of restricted stock outstanding	224,661		264,326		316,074
Restricted stock outstanding, weighted average grant date fair value	$ 27.08		$ 28.60		$ 34.21
Awarded and issued, weighted average grant date fair value	$ 33.70	[7]	$ 29.05	[7]	$ 19.33	[7]
Vested, weighted average grant date fair value	$ 30.64	[8]	$ 31.81	[8]	$ 33.38	[8]
Forfeited, weighted average grant date fair value	$ 0.00		$ 25.86		$ 31.26
Restricted stock outstanding, weighted average grant date fair value	$ 28.02		$ 27.08		$ 28.60
Fair value at grant date of restricted stock issued	2,600,000		2,600,000		2,500,000
Vesting date fair value of restricted stock	3,900,000		4,300,000		2,900,000
Weighted average grant date fair value of restricted stock	$ 33.70	[7]	$ 29.05	[7]	$ 19.33	[7]
Total Return-Based Restricted Stock [Member]
Compensation and Retirement Disclosure [Abstract]
Vesting period of stock options issued (in years)	3
Assumptions Used in Determining Fair Values of Options Granted:
Risk free interest rate	1.00%	[9]	1.30%	[9]	1.30%	[9]
Common stock dividend yield	5.40%	[4]	5.60%	[4]	7.60%	[4]
Expected volatility rate	42.80%	[10]	42.50%	[10]	37.80%	[10]
Dividends paid for previous year	1
Stock Option Activity Rollforward [Abstract]
Period for absolute total return (in years)	3
Percentage of return-based restricted stock issued to officers that will vest, minimum	0.00%
Percentage of return-based restricted stock issued to officers that will vest, maximum	250.00%
Restricted Stock Activity Rollforward [Abstract]
Balance of restricted stock outstanding	231,835		202,775		151,342
Awarded and issued	57,386	[11]	77,624	[11]	127,594	[11]
Vested	(66,417)	[12]	(47,257)	[12]	(68,929)	[12]
Forfeited	(99,975)		(1,307)		(7,232)
Balance of restricted stock outstanding	122,829		231,835		202,775
Restricted stock outstanding, weighted average grant date fair value	$ 21.03		$ 22.05		$ 33.39
Awarded and issued, weighted average grant date fair value	$ 41.02	[11]	$ 29.05	[11]	$ 15.01	[11]
Vested, weighted average grant date fair value	$ 13.79	[12]	$ 38.50	[12]	$ 32.66	[12]
Forfeited, weighted average grant date fair value	$ 13.79		$ 22.99		$ 34.14
Restricted stock outstanding, weighted average grant date fair value	$ 34.86		$ 21.03		$ 22.05
Fair value at grant date of restricted stock issued	2,400,000		2,300,000		1,900,000
Vesting date fair value of restricted stock	$ 2,000,000		$ 1,600,000		$ 2,600,000
Weighted average grant date fair value of restricted stock	$ 41.02	[11]	$ 29.05	[11]	$ 15.01	[11]

[1] We have 646,029 options exercisable at December 31, 2011 with weighted average exercise price of $31.01, weighted average remaining life of 2.4 years and intrinsic value of $1.1 million. Of these exercisable options, 252,277 had exercise prices higher than the market price of our Common Stock at December 31, 2011.

[2] The outstanding options at December 31, 2011 had a weighted average remaining life of 3.5 years.

[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 our historical data.

[7] The fair value at grant date of time-based restricted stock issued during the years ended December 31, 2011, 2010 and 2009 was $2.6 million, $2.6 million and $2.5 million, respectively.

[8] The vesting date fair value of time-based restricted stock that vested during the years ended December 31, 2011, 2010 and 2009 was $3.9 million, $4.3 million and $2.9 million, respectively.

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

[11] The fair value at grant date of total return-based restricted stock issued during the years ended December 31, 2011, 2010 and 2009 was $2.4 million, $2.3 million and $1.9 million, respectively. There were no performance-based restricted stock issued subsequent to 2008.

[12] The vesting date fair value of total return-based and other types performance-based restricted stock that vested during the years ended December 31, 2011, 2010 and 2009 was $2.0 million, $1.6 million and $2.6 million, respectively.