Debt (Debt Covenants and Compliance) (Details)	3 Months Ended
	Mar. 31, 2021 USD ($)	Oct. 01, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Cash and cash equivalents	$ 80,600,000				$ 55,200,000
Senior secured leverage ratio to consolidated EBITDA	2.26
Ratio of interest coverage	4.82
Actual total leverage ratio	3.18
Financing Agreement Senior Secured Credit Facility
Debt Instrument [Line Items]
Maximum annual dividend payment	$ 60,000,000.0
Maximum
Debt Instrument [Line Items]
Senior secured leverage ratio to consolidated EBITDA	3.50
Maximum | Financing Agreement Senior Secured Credit Facility
Debt Instrument [Line Items]
Total leverage ratio	2.75
Senior secured leverage ratio	3.00
Total leverage ratio on unsecured debt	3.50
Minimum
Debt Instrument [Line Items]
Ratio of interest coverage, covenant compliance	3.00
Senior Unsecured Notes
Debt Instrument [Line Items]
Interest rate, percentage	7.00%
Senior Secured Credit Facility
Debt Instrument [Line Items]
Cash and cash equivalents	$ 75,000,000.0
Total leverage ratio, covenant compliance	4.50
Effective total leverage ratio, covenant compliance	3.18
Senior Secured Credit Facility | Subsequent Event
Debt Instrument [Line Items]
Total leverage ratio, covenant compliance			4.125	4.25
Senior Secured Credit Facility | Maximum | Subsequent Event
Debt Instrument [Line Items]
Total leverage ratio, covenant compliance		3.75