Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Transition obligation period of recognition	20 years
Net actuarial loss that will be amortized from Accumulated other comprehensive income (loss) in next fiscal year	$ 3,000,000
Prior service credit that will be amortized from Accumulated other comprehensive income (loss) in next fiscal year	200,000
Assumptions used to determine benefit obligations [Abstract]
Discount rate (in hundredths)	3.50%	4.10%	5.15%
Expected long-term return on plan assets (in hundredths)	7.50%	7.50%	8.00%
Rate of compensation increase (in hundredths)	3.00%	3.00%	3.00%
Assumptions used to determine net periodic pension cost [Abstract]
Discount rate (in hundredths)	4.10%	5.15%	5.70%
Expected long-term return on plan assets (in hundredths)	7.50%	7.50%	8.00%
Rate of compensation increase (in hundredths)	3.00%	3.00%	3.00%
Estimate future benefit payments [Abstract]
Annual rates of increase in the per capita cost of covered medical and prescription drug benefits, minimum (in hundredths)	6.00%
Annual rates of increase in the per capita cost of covered medical and prescription drug benefits, maximum (in hundredths)	6.50%
Ultimate health care cost trend rate (in hundredths)	5.00%
Actual plan asset allocations [Abstract]
Actual plan asset allocations (in hundredths)	100.00%	100.00%
Employer contributions to 401 (k) plan	1,800,000	3,700,000	3,500,000
Effect of one-percentage point change in assumed health care cost trend rates [Abstract]
One-percentage point Increase on total service and interest cost components	24,000
One-percentage point (decrease) on total service and interest cost components	(20,000)
One-percentage point Increase on postretirement accumulated benefit obligation	503,000
One-percentage point (decrease) on postretirement accumulated benefit obligation	(426,000)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards termination period	10 years
Stock options additional disclosures [Abstract]
Stock-based compensation expense	4,364,000	3,244,000	3,782,000
Restricted Stock and restricted stock additional disclosures [Abstract]
Number of shares available for future grant (in shares)	4,400,000
Fair value assumptions [Abstract]
Dividend yield (in hundredths)	3.94%
Dividend yield, minimum (in hundredths)		3.31%	3.27%
Dividend yield, maximum (in hundredths)		3.82%	3.96%
Expected volatility (in hundredths)	34.64%
Expected volatility, minimum (in hundredths)		33.75%	33.00%
Expected volatility, maximum (in hundredths)		34.36%	33.86%
Risk-free interest rates (in hundredths)	1.24%
Risk-free interest rates, minimum (in hundredths)		1.48%	1.90%
Risk-free interest rates, maximum (in hundredths)		2.81%	3.17%
Expected life (in years)	7	7	7
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vesting period	4 years
Weighted average fair value of stock options granted (in dollars per share)	$ 4.57	$ 5.45	$ 5.03
Stock options [Roll Forward]
Outstanding, Beginning of period (in shares)	1,863,590
Granted (in shares)	150
Exercised (in shares)	(108,817)
Forfeited (in shares)	(11,150)
Expired (in shares)	(48,211)
Outstanding, End of period (in shares)	1,695,562	1,863,590
Exercisable, End of period (in shares)	1,480,737
Expected to Vest (in shares)	205,476
Stock options additional disclosures [Abstract]
Weighted average exercise price, Outstanding, Beginning of period (in dollars per share)	$ 22.41
Weighted average exercise price, Granted (in dollars per share)	$ 20.30
Weighted average exercise price, Exercised (in dollars per share)	$ 17.53
Weighted average exercise price, Forfeited (in dollars per share)	$ 21.92
Weighted average exercise price, Expired (in dollars per share)	$ 22.50
Weighted average exercise price, Outstanding, End of period (in dollars per share)	$ 22.72	$ 22.41
Weighted average exercise price, Exercisable, End of period (in dollars per share)	$ 22.83
Weighted average exercise price, Expected to Vest (in dollars per share)	$ 21.97
Weighted Average Remaining Contractual Term, Outstanding, End of period (in years)	4.58
Weighted Average Remaining Contractual Term, Exercisable, End of period (in years)	4.21
Weighted Average Remaining Contractual Term, Expected to Vest (in years)	7.01
Aggregate Intrinsic Value, Outstanding, End of period	51,236
Aggregate Intrinsic Value, Exercisable, End of period	43,043
Aggregate Intrinsic Value, Expected to Vest	7,752
Stock-based compensation expense	500,000	900,000	1,800,000
Proceeds from stock options exercised	1,908,000	2,255,000	1,778,000
Tax benefits related to stock options exercised	8,000	341,000	140,000
Intrinsic value of stock options exercised	498,000	897,000	574,000
Fair value of shares vested during the year	1,656,000	1,597,000	1,800,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares vesting period for employees, minimum	5 years
Restricted shares vesting period for non-employee directors, minimum	3 years
Stock options additional disclosures [Abstract]
Unrecognized compensation cost	4,700,000
Unrecognized compensation cost, weighted average period of recognition (in years)	2.5
Restricted Stock and restricted stock [Roll Forward]
Unvested, Beginning of period (in shares)	155,376
Forfeited (in shares)	(3,500)
Vested (in shares)	(34,726)
Unvested, End of period (in shares)	117,150
Restricted Stock and restricted stock additional disclosures [Abstract]
Weighted-average grant date fair value, Unvested, Beginning of period (in dollars per share)	$ 23.92
Weighted-average grant date fair value, Forfeited (in dollars per share)	$ 21.96
Weighted-average grant date fair value, Vested (in dollars per share)	$ 22.61
Weighted-average grant date fair value, Unvested, End of period (in dollars per share)	$ 24.36
Restricted Stock Units (RSUs) [Member]
Restricted Stock and restricted stock [Roll Forward]
Unvested, Beginning of period (in shares)	241,907
Forfeited (in shares)	(5,103)
Vested (in shares)	(37,068)
Granted (in shares)	206,322
Unvested, End of period (in shares)	406,058
Restricted Stock and restricted stock additional disclosures [Abstract]
Weighted-average grant date fair value, Unvested, Beginning of period (in dollars per share)	$ 23.95
Weighted-average grant date fair value, Forfeited (in dollars per share)	$ 0
Weighted-average grant date fair value, Vested (in dollars per share)	$ 0
Weighted-average grant date fair value, Granted (in dollars per share)	$ 22.38
Weighted-average grant date fair value, Unvested, End of period (in dollars per share)	$ 25.64
Restricted and Deferred Stock Awards [Member]
Stock options additional disclosures [Abstract]
Stock-based compensation expense	3,700,000	3,200,000	2,000,000
Tax benefit from compensation expense	1,500,000	1,200,000	700,000
Pension Benefits [Member]
Accumulated other comprehensive income (loss), before tax [Abstract]
Net actuarial loss	35,478,000	37,914,000
Prior service cost	141,000	1,430,000
Total amounts recognized in accumulated other comprehensive loss (pre-tax)	35,619,000	39,344,000
Change in benefit obligation [Roll Forward]
Benefit obligation at beginning of period	78,024,000	70,229,000
Service cost	3,122,000	2,589,000	2,254,000
Interest cost	3,145,000	3,544,000	3,613,000
Plan participants' contributions	0	0
Actuarial loss (gain)	5,941,000	5,935,000
Amendments	(1,006,000)	0
Benefits paid	(4,097,000)	(4,273,000)
Projected benefit obligation at end of period	85,129,000	78,024,000	70,229,000
Change in plan assets [Roll Forward]
Fair value of plan assets at beginning of period	91,575,000	97,821,000
Actual return (loss) on plan assets	11,733,000	(2,452,000)
Employer contributions	493,000	479,000
Plan participants' contributions	0	0
Benefits paid	(4,097,000)	(4,273,000)
Fair value of plan assets at end of period	99,704,000	91,575,000	97,821,000
Funded status	14,575,000	13,551,000
Accumulated benefit obligation	84,500,000	76,500,000
Amounts recognized in Balance Sheet [Abstract]
Other assets	27,062,000	23,972,000
Other liabilities	(12,487,000)	(10,421,000)
Funded status	14,575,000	13,551,000
Components of net periodic benefit cost [Abstract]
Service cost	3,122,000	2,589,000	2,254,000
Interest cost	3,145,000	3,544,000	3,613,000
Expected return on plan assets	(6,686,000)	(7,720,000)	(7,166,000)
Amortization of prior service cost	283,000	309,000	322,000
Amortization of unrecognized net loss	3,330,000	1,353,000	1,447,000
Net periodic pension cost	3,194,000	75,000	470,000
Other changes in plan assets and benefit obligation recognized in other comprehensive income (pre-tax) [Abstract]
Net loss (gain)	894,000	16,108,000	1,620,000
Prior service cost	(1,006,000)	0	21,000
Amortization of prior service cost	(283,000)	(309,000)	(322,000)
Amortization of unrecognized net gain	(3,330,000)	(1,353,000)	(1,447,000)
Total recognized in other comprehensive loss (income)	(3,725,000)	14,446,000	(128,000)
Total recognized in net periodic benefit cost and other comprehensive income (loss) - pre-tax	(531,000)	14,521,000	342,000
Estimate future benefit payments [Abstract]
2013	5,247,000
2014	5,243,000
2015	5,285,000
2016	7,767,000
2017	5,942,000
2018 - 2022	29,180,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	99,704,000	91,575,000	97,821,000
Pension Benefits [Member] | Level 1 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	70,414,000	60,043,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	70,414,000	60,043,000
Pension Benefits [Member] | Level 2 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	29,290,000	31,532,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	29,290,000	31,532,000
Pension Benefits [Member] | Level 3 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Cash and Cash Equivalents [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at beginning of period	1,503,000
Fair value of plan assets at end of period	5,464,000
Target asset allocations [Abstract]
Target allocation percentage of assets, range minimum (in hundredths)	0.00%
Target allocation percentage of assets, range maximum (in hundredths)	20.00%
Actual plan asset allocations [Abstract]
Actual plan asset allocations (in hundredths)	5.00%	2.00%
Fair value of plan assets	5,464,000
Pension Benefits [Member] | Cash and Cash Equivalents [Member] | Level 1 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	5,464,000	1,503,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	5,464,000	1,503,000
Pension Benefits [Member] | Cash and Cash Equivalents [Member] | Level 2 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Cash and Cash Equivalents [Member] | Level 3 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Fixed Income Securities [Member]
Target asset allocations [Abstract]
Target allocation percentage of assets, range minimum (in hundredths)	20.00%
Target allocation percentage of assets, range maximum (in hundredths)	40.00%
Actual plan asset allocations [Abstract]
Actual plan asset allocations (in hundredths)	29.00%	34.00%
Pension Benefits [Member] | Equity Securities [Member]
Target asset allocations [Abstract]
Target allocation percentage of assets, range minimum (in hundredths)	40.00%
Target allocation percentage of assets, range maximum (in hundredths)	80.00%
Actual plan asset allocations [Abstract]
Actual plan asset allocations (in hundredths)	66.00%	64.00%
Pension Benefits [Member] | Foreign Equity Mutual Funds [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	9,763,000	6,577,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	9,763,000	6,577,000
Pension Benefits [Member] | Foreign Equity Mutual Funds [Member] | Level 1 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	9,763,000	6,577,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	9,763,000	6,577,000
Pension Benefits [Member] | Foreign Equity Mutual Funds [Member] | Level 2 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Foreign Equity Mutual Funds [Member] | Level 3 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Equity Mutual Funds [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	13,110,000	9,902,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	13,110,000	9,902,000
Pension Benefits [Member] | Equity Mutual Funds [Member] | Level 1 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	13,110,000	9,902,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	13,110,000	9,902,000
Pension Benefits [Member] | Equity Mutual Funds [Member] | Level 2 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Equity Mutual Funds [Member] | Level 3 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | US Government Bonds [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	12,744,000	15,683,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	12,744,000	15,683,000
Pension Benefits [Member] | US Government Bonds [Member] | Level 1 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | US Government Bonds [Member] | Level 2 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	12,744,000	15,683,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	12,744,000	15,683,000
Pension Benefits [Member] | US Government Bonds [Member] | Level 3 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Corporate Bonds [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	13,604,000	12,954,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	13,604,000	12,954,000
Pension Benefits [Member] | Corporate Bonds [Member] | Level 1 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Corporate Bonds [Member] | Level 2 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	13,604,000	12,954,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	13,604,000	12,954,000
Pension Benefits [Member] | Corporate Bonds [Member] | Level 3 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Common Stock [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	40,430,000	33,850,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	40,430,000	33,850,000
Pension Benefits [Member] | Common Stock [Member] | Level 1 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	40,430,000	33,850,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	40,430,000	33,850,000
Pension Benefits [Member] | Common Stock [Member] | Level 2 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Common Stock [Member] | Level 3 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Municipal Bonds and Notes [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	1,805,000	1,799,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	1,805,000	1,799,000
Pension Benefits [Member] | Municipal Bonds and Notes [Member] | Level 1 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Municipal Bonds and Notes [Member] | Level 2 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	1,805,000	1,799,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	1,805,000	1,799,000
Pension Benefits [Member] | Municipal Bonds and Notes [Member] | Level 3 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Foreign Bonds and Notes [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	1,137,000	1,096,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	1,137,000	1,096,000
Pension Benefits [Member] | Foreign Bonds and Notes [Member] | Level 1 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Foreign Bonds and Notes [Member] | Level 2 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	1,137,000	1,096,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	1,137,000	1,096,000
Pension Benefits [Member] | Foreign Bonds and Notes [Member] | Level 3 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Foreign Equity [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	1,647,000	8,211,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	1,647,000	8,211,000
Pension Benefits [Member] | Foreign Equity [Member] | Level 1 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	1,647,000	8,211,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	1,647,000	8,211,000
Pension Benefits [Member] | Foreign Equity [Member] | Level 2 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Pension Benefits [Member] | Foreign Equity [Member] | Level 3 [Member]
Change in plan assets [Roll Forward]
Fair value of plan assets at end of period	0	0
Actual plan asset allocations [Abstract]
Fair value of plan assets	0	0
Other Benefits [Member]
Accumulated other comprehensive income (loss), before tax [Abstract]
Net actuarial loss	2,277,000	2,323,000
Prior service cost	(672,000)	(874,000)
Total amounts recognized in accumulated other comprehensive loss (pre-tax)	1,605,000	1,449,000
Change in benefit obligation [Roll Forward]
Benefit obligation at beginning of period	3,985,000	4,554,000
Service cost	20,000	17,000	17,000
Interest cost	155,000	202,000	228,000
Plan participants' contributions	233,000	263,000
Actuarial loss (gain)	136,000	(562,000)
Amendments	0	0
Benefits paid	(458,000)	(489,000)
Projected benefit obligation at end of period	4,071,000	3,985,000	4,554,000
Change in plan assets [Roll Forward]
Fair value of plan assets at beginning of period	0	0
Actual return (loss) on plan assets	0	0
Employer contributions	225,000	226,000
Plan participants' contributions	233,000	263,000
Benefits paid	(458,000)	(489,000)
Fair value of plan assets at end of period	0	0	0
Funded status	(4,071,000)	(3,985,000)
Accumulated benefit obligation	4,100,000	4,000,000
Amounts recognized in Balance Sheet [Abstract]
Other assets	0	0
Other liabilities	(4,071,000)	(3,985,000)
Funded status	(4,071,000)	(3,985,000)
Components of net periodic benefit cost [Abstract]
Service cost	20,000	17,000	17,000
Interest cost	155,000	202,000	228,000
Expected return on plan assets	0	0	0
Amortization of prior service cost	(202,000)	(202,000)	(202,000)
Amortization of unrecognized net loss	182,000	205,000	201,000
Net periodic pension cost	155,000	222,000	244,000
Other changes in plan assets and benefit obligation recognized in other comprehensive income (pre-tax) [Abstract]
Net loss (gain)	136,000	(562,000)	955,000
Prior service cost	0	0	0
Amortization of prior service cost	202,000	202,000	202,000
Amortization of unrecognized net gain	(182,000)	(205,000)	(201,000)
Total recognized in other comprehensive loss (income)	156,000	(565,000)	956,000
Total recognized in net periodic benefit cost and other comprehensive income (loss) - pre-tax	311,000	(343,000)	1,200,000
Estimate future benefit payments [Abstract]
2013	215,000
2014	224,000
2015	234,000
2016	242,000
2017	250,000
2018 - 2022	1,311,000
Actual plan asset allocations [Abstract]
Fair value of plan assets	$ 0	$ 0	$ 0