Derivative Instruments and Hedging Activities (Details)		12 Months Ended
	Jun. 19, 2018	Dec. 31, 2019 USD ($)	Dec. 31, 2014 USD ($) instrument	Dec. 31, 2011
Derivatives Fair Value [Line Items]
Basis spread on variable rate		1.375%
Excess line of credit facility subject to interest rate risk		$ 25,000,000
Long-term debt, percentage bearing fixed interest, amount		175,000,000
Long-term debt, percentage bearing variable interest, amount		$ 132,000,000
Interest Rate Swap [Member]
Derivatives Fair Value [Line Items]
Derivative, number of instruments held | instrument			2
Derivative, notional amount			$ 50,000,000
Derivative, amount of hedged item			50,000,000
Interest Rate Swap No. 1 [Member]
Derivatives Fair Value [Line Items]
Derivative, notional amount			$ 25,000,000
Derivative, Fixed Interest Rate			2.50%
Derivative, maturity date			Aug. 29, 2024
Interest Rate Swap No. 2 [Member]
Derivatives Fair Value [Line Items]
Derivative, notional amount			$ 25,000,000
Derivative, Fixed Interest Rate			2.50%
Derivative, maturity date			Aug. 29, 2019
Senior Notes Series A [Member]
Derivatives Fair Value [Line Items]
Interest rate, effective percentage				4.01%
Senior Notes Series B [Member]
Derivatives Fair Value [Line Items]
Interest rate, effective percentage				4.11%
Maximum [Member]
Derivatives Fair Value [Line Items]
Basis spread on variable rate	2.00%	2.00%