Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2012

Schedule of reconciliation of the changes in the benefit obligations

													Supplemental executive
	Defined benefit pension plan						Post-retirement medical plan						retirement plan						Total
	2012			2011			2012			2011			2012			2011			2012			2011

Change in projected benefit obligation:
Benefit obligation, January 1	$	401,134		$	349,435		$	11,725		$	10,162		$	61,358		$	54,855		$	474,217		$	414,452
Service cost	4,350			3,935			817			622			991			916			6,158			5,473
Interest cost	20,945			20,286			569			585			2,912			3,136			24,426			24,007
Actuarial (gain) loss	87,117			39,211			974			693			6,760			3,520			94,851			43,424
Regular benefits paid	(12,943		)	(11,733		)	(623		)	(337		)	(2,792		)	(2,719		)	(16,358		)	(14,789		)
Plan amendments	—			—			—			—			—			1,650			—			1,650
Benefit obligation, December 31	$	500,603		$	401,134		$	13,462		$	11,725		$	69,229		$	61,358		$	583,294		$	474,217
Accumulated benefit obligation	$	491,712		$	393,487		$	13,462		$	11,725		$	58,135		$	50,033		$	563,309		$	455,245

Schedule of fair value of plan assets

													Supplemental executive
	Defined benefit pension plan						Post-retirement medical plan						retirement plan						Total
	2012			2011			2012			2011			2012			2011			2012			2011

Change in plan assets:
Value of plan assets, January 1	$	293,336		$	282,616		$	—		$	—		$	—		$	—		$	293,336		$	282,616
Actual return on plan assets	38,541			12,353			—			—			—			—			38,541			12,353
Employer contributions	17,600			10,100			623			337			2,792			2,719			21,015			13,156
Benefits paid	(12,943		)	(11,733		)	(623		)	(337		)	(2,792		)	(2,719		)	(16,358		)	(14,789		)
Value of plan assets, December 31	$	336,534		$	293,336		$	—		$	—		$	—		$	—		$	336,534		$	293,336

Schedule of fair value of plan assets and the underfunded status

											Supplemental executive
	Defined benefit pension plan						Post-retirement medical plan						retirement plan						Total
	2012			2011			2012			2011			2012			2011			2012			2011

Under funded status at December 31	$	(164,069	)	$	(107,798	)	$	(13,462	)	$	(11,725	)	$	(69,229	)	$	(61,358	)	$	(246,760	)	$	(180,881	)

Schedule of amounts recognized in the consolidated balance sheets

													Supplemental executive
	Defined benefit pension plan						Post-retirement medical plan						retirement plan						Total
	2012			2011			2012			2011			2012			2011			2012			2011

Amounts recognized in consolidated balance sheets:
Other assets	$	—		$	12,690		$	—		$	—		$	—		$	—		$	—		$	12,690
Other liabilities	(164,069		)	(120,488		)	(13,462		)	(11,725		)	(69,229		)	(61,358		)	(246,760		)	(193,571		)
Accumulated other comprehensive income (loss)	(180,869		)	(120,487		)	12,662			15,741			(20,710		)	(15,520		)	(188,917		)	(120,266		)

Schedule of amounts recognized in AOCI that have not yet been recognized as components of net periodic benefit costs

											Supplemental executive
	Defined benefit pension plan						Post-retirement medical plan				retirement plan						Total
	Gross			Net of tax			Gross		Net of tax		Gross			Net of tax			Gross			Net of tax

Net gain (loss)	$	(180,754	)	$	(117,490	)	$	6,170	$	4,011	$	(15,710	)	$	(10,211	)	$	(190,294	)	$	(123,690	)
Net prior service (cost) credit	(115		)	(75		)	6,492		4,220		(5,000		)	(3,250		)	1,377			895
	$	(180,869	)	$	(117,565	)	$	12,662	$	8,231	$	(20,710	)	$	(13,461	)	$	(188,917	)	$	(122,795	)

Schedule of information regarding amounts in AOCI that are expected to be recognized as components of net periodic benefit costs during the next fiscal year

											Supplemental executive
	Defined benefit pension plan						Post-retirement medical plan				retirement plan						Total
	Gross			Net of tax			Gross		Net of tax		Gross			Net of tax			Gross			Net of tax

Net gain (loss)	$	(15,577	)	$	(10,125	)	$	413	$	268	$	(1,300	)	$	(845	)	$	(16,464	)	$	(10,702	)
Prior service (cost) credit	(51		)	(33		)	1,650		1,072		(933		)	(606		)	666			433
	$	(15,628	)	$	(10,158	)	$	2,063	$	1,340	$	(2,233	)	$	(1,451	)	$	(15,798	)	$	(10,269	)

Schedule of expected benefit payments

					Supplemental
	Defined benefit		Post-retirement		executive
	pension plan		medical plan		retirement plan

2013	$	13,621	$	637	$	3,720
2014	14,259		697		3,529
2015	15,136		727		4,940
2016	16,640		743		3,390
2017	17,708		771		18,909
2018 through 2022	112,582		4,166		13,813

Schedule of net periodic (benefit) cost

	Defined benefit pension plan
	2012			2011			2010

Components of net periodic cost:
Service cost	$	4,350		$	3,935		$	3,739
Interest cost	20,945			20,286			19,578
Expected return on plan assets	(21,797		)	(21,093		)	(18,618		)
Amortization of transition obligation	—			(1,388		)	(1,514		)
Amortization of unrecognized prior service cost	51			51			82
Amortization of loss from earlier periods	9,941			5,115			5,091
Net periodic cost	$	13,490		$	6,906		$	8,358

	Post-retirement medical plan
	2012			2011			2010

Components of net periodic benefit:
Service cost	$	817		$	622		$	728
Interest cost	569			585			713
Amortization of unrecognized prior service benefit	(1,650		)	(1,650		)	(1,650		)
Amortization of gain from earlier periods	(455		)	(611		)	(461		)
Net periodic benefit	$	(719	)	$	(1,054	)	$	(670	)

	Supplemental executive retirement plan
	2012		2011		2010

Components of net periodic (benefit) cost:
Service cost	$	991	$	916	$	673
Interest cost	2,912		3,136		2,905
Amortization of unrecognized prior service cost	934		2,584		899
Amortization of net (gain) loss	637		145		—
Net periodic (benefit) cost	$	5,474	$	6,781	$	4,477

Schedule of weighted average interest rate assumptions used in determining benefit obligations

	Defined benefit pension plan
	2012		2011

Discount rate	4.19	%	5.23	%
Rate of compensation increase	3.14	%	3.14	%

	Post-retirement medical plan
	2012		2011

Discount rate	3.74	%	4.70	%
Initial health care cost trend	7.50	%	8.00	%
Ultimate health care cost trend	5.25	%	5.25	%
Year ultimate trend is reached	2018		2018

	Supplemental executive
	retirement plan
	2011		2011

Discount rate	3.79	%	4.87	%
Rate of compensation increase	4.00	%	5.00	%

Schedule of weighted average interest rate assumptions used in determining the net periodic benefit/cost

	Defined benefit pension plan
	2012		2011

Discount rate	5.23	%	5.87	%
Expected return on plan assets	7.25	%	7.50	%
Rate of compensation increase	3.14	%	3.14	%

	Post-retirement medical plan
	2012		2011

Discount rate	4.70	%	5.87	%
Initial health care cost trend	8.00	%	7.50	%
Ultimate health care cost trend	5.25	%	5.25	%
Year ultimate trend is reached	2018		2016

	Supplemental executive
	retirement plan
	2012		2011

Discount rate	4.87	%	5.87	%
Rate of compensation increase	5.00	%	6.00	%

Schedule of effect of one-percentage-point change in assumed healthcare cost trend rates

	One percentage		One percentage
	point increase		point decrease

Increase (decrease) on total service and interest cost on components	$	199	$	(170	)
Increase (decrease) on post-retirement benefit obligation	1,448		(1,260		)

Schedule of investment of defined benefit pension plan assets

	December 31,
	2012		2011

Equity securities	56	%	52	%
Debt securities	41	%	44	%
Other	3	%	4	%
Total	100	%	100	%

Schedule of defined benefit retirement plan assets measured at fair value on a recurring basis

	Defined Benefit Plan Assets Measured at Fair Value on a Recurring Basis
	December 31, 2012
	Quoted prices		Significant
	in active		other		Significant
	markets for		observable		unobservable
	identical assets		inputs		inputs
	(Level 1)		(Level 2)		(Level 3)		Total

Common collective trust funds:
Equity index funds	$	—	$	60,601	$	—	$	60,601
Midcap index funds	—		60,289		—		60,289
World equity index funds	—		6,798		—		6,798
U.S. equity market funds	—		60,723		—		60,723
Total common collective trust funds	—		188,411		—		188,411

Fixed maturity investments:
U.S. government direct obligations and agencies	—		9,907		—		9,907
Obligations of U.S. states and their municpalities	—		16,899		—		16,899
Corporate debt securities	—		100,142		—		100,142
Asset-backed securities	—		8,386		—		8,386
Commercial mortgage-backed securities	—		2,961		—		2,961
Total fixed maturity investments	—		138,295		—		138,295

Preferred stock	134		—		—		134
Limited partnership investments	—		—		6,485		6,485
Money market funds	3,209		—		—		3,209
Total defined benefit plan assets	$	3,343	$	326,706	$	6,485	$	336,534

	Defined Benefit Plan Assets Measured at Fair Value on a Recurring Basis
	December 31, 2011
	Quoted prices		Significant
	in active		other		Significant
	markets for		observable		unobservable
	identical assets		inputs		inputs
	(Level 1)		(Level 2)		(Level 3)		Total

Common collective trust funds:
Equity index funds	$	—	$	49,211	$	—	$	49,211
Midcap index funds	—		48,406		—		48,406
World equity index funds	—		5,336		—		5,336
U.S. equity market funds	—		48,972		—		48,972
Total common collective trust funds	—		151,925		—		151,925

Fixed maturity investments:
U.S. government direct obligations and agencies	—		10,676		—		10,676
Obligations of U.S. states and their municpalities	—		22,467		—		22,467
Corporate debt securities	—		86,836		—		86,836
Asset-backed securities	—		7,711		—		7,711
Commercial mortgage-backed securities	—		2,487		—		2,487
Total fixed maturity investments	—		130,177		—		130,177

Preferred stock	—		111		—		111
Limited partnership investments	—		—		7,116		7,116
Money market funds	4,007		—		—		4,007
Total defined benefit plan assets	$	4,007	$	282,213	$	7,116	$	293,336

Schedule of defined benefit retirement plan assets measured at fair value on a recurring basis for which Level 3 inputs are utilized

	Fair Value Measurements Using
	Significant Unobservable Inputs (Level 3)
	Limited partnership interest
	2012			2011

Balance, January 1	$	7,116		$	6,030
Actual return on plan assets
Purchases	61			(34		)
Issuances	(692		)	1,542
Settlement				(422		)
Balance, December 31	$	6,485		$	7,116

Schedule of targets for the allocation of invested Defined Benefit Pension Plan assets

		December 31, 2013

Equity securities		25% - 80%
Debt securities		25% - 75%
Other		0% - 40%