Short-Term Borrowings Additional Information (Details) $ in Thousands		3 Months Ended
		Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Short-term Debt [Line Items]
Line of Credit, Additional Capacity, COVID		$ 50,000
Line of Credit, Additional Capacity		$ 45,000
Basis plus LIBOR for Rate Swaps		35
Basis plus LIBOR, interest for Rate Swaps		175
Number of short term lines of Credit, Additional		2
Ratio of Indebtedness to Net Capital		0.65
Short Term Borrowing, BOD Maximum Limit		$ 400,000
Short-term Debt		254,339	$ 247,371
Line Of Credit Facility Maximum Borrowing Committed Capacity		220,000
Notional Amount of Nonderivative Instruments		$ 70,000
Number of short-term lines of Credit, rate swap		2
Short-term Debt, Weighted Average Interest Rate, at Point in Time		2.30%	2.62%
ParticipatingLendersInTheRevolver		5
Line of Credit Facility, Maximum Borrowing Capacity		$ 370,000
Number Of Unsecured Bank Credit Facilities		4
Number Of Financial Institutions With Bank Credit Facilities		4
Swap Facility 1 [Member]
Short-term Debt [Line Items]
Fixed Swap Rate		38.75%
Swap Facility 2 [Member]
Short-term Debt [Line Items]
Fixed Swap Rate		27.50%
Committed Line of Credit Facility Four [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	[1]	$ 150,000

[1] ⁽²⁾ This committed revolving credit facility includes a restriction that our short-term borrowings, excluding any borrowings under the committed revolving credit facility, shall not exceed $350.0 million.