Compensation Plans: Stock Based (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) shares $ / shares	Dec. 31, 2020 USD ($) shares $ / shares	Dec. 31, 2019 USD ($) shares $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant	4,900,000
Impact outright issuance of one share has on number of available shares	1
Performance Shares (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum impact of issuance of one performance share award on available shares under the equity incentive plan	2
Multiplier applied to PSU awards at settlement	1.0	0.9	0
Award vesting period	3 years
Retirement vesting Increment	6 months
Retirement increment vesting period	6 months
TSR multiplier cap	1
Stock-based compensation expense | $	$ 6.0	$ 4.4	$ 10.9
Unrecognized stock based compensation expense | $	$ 1.4
Non-vested at beginning of year (in shares)	830,464	2,022,585	1,711,259
Non-vested outstanding at the beginning of the period grant date fair value ($/share) | $ / shares	$ 17.52	$ 16.87	$ 20.68
Granted (in shares)	0	0	793,125
Granted grant date fair value ($/share) | $ / shares	$ 0	$ 0	$ 12.80
Vested (in shares)	(352,395)	(792,572)	(346,021)
Vested grant date fair value ($/share) | $ / shares	$ 23.81	$ 15.85	$ 26.32
Forfeited (in shares)	(13,586)	(399,549)	(135,778)
Forfeited grant date fair value ($/share) | $ / shares	$ 15.46	$ 17.56	$ 16.98
Non-vested at end of year (in shares)	464,483	830,464	2,022,585
Non-vested outstanding at the end of the period grant date fair value ($/share) | $ / shares	$ 12.80	$ 17.52	$ 16.87
Multiplier assumed	1	1	1
Performance share units, shares settled gross of shares for tax withholdings	347,742	700,511	0
Fair value of PSUs/RSUs granted in period | $			$ 10.2
Shares held for settlement of income and payroll tax obligations (in shares)	(112,919)	(215,451)
Shares Issued in Period	234,823	485,060
Fair value of PSUs/RSUs Vested in Period | $	$ 8.4	$ 12.6	9.1
Performance Shares (PSUs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Multiplier applied to PSU awards at settlement	0
Performance Shares (PSUs) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Multiplier applied to PSU awards at settlement	2
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Retirement vesting Increment	6 months
Retirement increment vesting period	6 months
Stock-based compensation expense | $	$ 10.2	$ 8.7	$ 11.1
Unrecognized stock based compensation expense | $	$ 20.7
Non-vested at beginning of year (in shares)	2,097,860	1,532,131	1,243,163
Non-vested outstanding at the beginning of the period grant date fair value ($/share) | $ / shares	$ 8.83	$ 16.01	$ 21.50
Granted (in shares)	666,052	1,458,869	978,932
Granted grant date fair value ($/share) | $ / shares	$ 25.52	$ 5.98	$ 12.36
Vested (in shares)	(843,098)	(746,132)	(466,535)
Vested grant date fair value ($/share) | $ / shares	$ 11.00	$ 16.74	$ 21.94
Forfeited (in shares)	(79,577)	(147,008)	(223,429)
Forfeited grant date fair value ($/share) | $ / shares	$ 10.64	$ 15.34	$ 18.16
Non-vested at end of year (in shares)	1,841,237	2,097,860	1,532,131
Non-vested outstanding at the end of the period grant date fair value ($/share) | $ / shares	$ 13.79	$ 8.83	$ 16.01
Performance share units, shares settled gross of shares for tax withholdings	843,098	746,132	466,535
Number of Shares Represented by Each RSU	1
Fair value of PSUs/RSUs granted in period | $	$ 17.0	$ 8.7	$ 12.1
Shares held for settlement of income and payroll tax obligations (in shares)	(250,349)	(209,173)	(132,136)
Shares Issued in Period	592,749	536,959	334,399
Fair value of PSUs/RSUs Vested in Period | $	$ 9.3	$ 12.5	$ 10.2