Benefit Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 17, 2009
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		$ 0	$ 0
Defined Benefit Plan, Benefit Obligation		$ 184,410,000	$ 154,419,000	$ 123,528,000
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		3.00%	3.53%	4.60%
Expected long-term rate of return on plan assets		7.00%
Accumulated benefit obligation for the pension plan		$ 149,500,000	$ 129,300,000
Common share purchased under pension plan, shares					115,800
Common share purchased under pension plan, value					$ 7,000,000.0
Common share purchased under pension plan, value per share					$ 60.45
Fair value of common shares held by pension plan		$ 12,200,000	$ 11,900,000
Fair value of common shares held by pension plan, per share		$ 105.01	$ 102.38
Fair value, pension plan common shares held, shares		115,800
Estimated net actuarial (loss) expected to be recognized in the next fiscal year		$ 2,200,000
Defined Benefit Plan, Plan Assets, Amount		230,442,000	$ 210,623,000	$ 177,077,000
Market value of pension plan assets		230,400,000	210,600,000
Defined Contribution Plan, Cost		4,200,000	3,900,000	3,000,000.0
Subsequent Event [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 0
Level 1
Defined Benefit Plan Disclosure [Line Items]
Equity investments		195,000,000.0	180,000,000.0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Equity investments		35,400,000	30,600,000
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Equity investments		0	0
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		2,500,000
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated prior service costs expected to be recognized in net periodic benefit cost during next fiscal year		(16,000)
Supplemental Executive Retirement Plan (SERP)
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit cost		12,300,000	11,000,000.0
Benefit expense		$ 2,100,000	$ 1,300,000	$ 1,000,000.0