Derivatives (Outstanding Interest Rate Derivatives) (Details) - Long-term $ in Millions	Mar. 31, 2021 USD ($)
Not Accounted for as Hedge | Swap 1.9%
Derivative [Line Items]
Notional amount	$ 23.0
Interest rate	1.90%
Not Accounted for as Hedge | Collar 3.5% to 4.8%
Derivative [Line Items]
Notional amount	$ 40.0
Not Accounted for as Hedge | Collar 3.5% to 4.8% | Minimum
Derivative [Line Items]
Interest rate	3.50%
Not Accounted for as Hedge | Collar 3.5% to 4.8% | Maximum
Derivative [Line Items]
Interest rate	4.80%
Not Accounted for as Hedge | Swap 0.0% to 0.8% | Minimum
Derivative [Line Items]
Interest rate	0.00%
Not Accounted for as Hedge | Swap 0.0% to 0.8% | Maximum
Derivative [Line Items]
Interest rate	0.80%
Not Accounted for as Hedge | Swap 0.0% to 0.7% | Minimum
Derivative [Line Items]
Interest rate	0.00%
Not Accounted for as Hedge | Swap 0.0% to 0.7% | Maximum
Derivative [Line Items]
Interest rate	0.70%
Not Accounted for as Hedge | Swap 0.0% to 0.8% | Minimum
Derivative [Line Items]
Interest rate	0.00%
Not Accounted for as Hedge | Swap 0.0% to 0.8% | Maximum
Derivative [Line Items]
Interest rate	0.80%
Not Accounted for as Hedge | Swap 0.0% to 0.8% | Minimum
Derivative [Line Items]
Interest rate	0.00%
Not Accounted for as Hedge | Swap 0.0% to 0.8% | Maximum
Derivative [Line Items]
Interest rate	0.80%
Accounted for as Hedge | Swap 1.8%
Derivative [Line Items]
Notional amount	$ 20.0
Interest rate	1.80%
Accounted for as Hedge | Swap 2.6%
Derivative [Line Items]
Notional amount	$ 10.0
Interest rate	2.60%
Accounted for as Hedge | Swap 2.7%
Derivative [Line Items]
Notional amount	$ 20.0
Interest rate	2.70%
Accounted for as Hedge | Swap 2.5%
Derivative [Line Items]
Notional amount	$ 100.0
Interest rate	2.50%
Accounted for as Hedge | Swap 2.5%
Derivative [Line Items]
Notional amount	$ 50.0
Interest rate	2.50%
Accounted for as Hedge | Swap 2.5%
Derivative [Line Items]
Notional amount	$ 50.0
Interest rate	2.50%
Accounted for as Hedge | Swap 0.0% to 0.8%
Derivative [Line Items]
Notional amount	$ 50.0
Accounted for as Hedge | Swap 0.0% to 0.7%
Derivative [Line Items]
Notional amount	50.0
Accounted for as Hedge | Swap 0.0% to 0.8%
Derivative [Line Items]
Notional amount	50.0
Accounted for as Hedge | Swap 0.0% to 0.8%
Derivative [Line Items]
Notional amount	$ 50.0