Net Gains (Losses) on Cash Flow Hedging Relationships (Details) - Forward-start interest rate swaps [Member] - COs - bonds [Member] - Designated as Hedging Instrument [Member] - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Losses reclassified from accumulated other comprehensive loss into interest expense	$ (1,757)
Losses reclassified from accumulated other comprehensive loss into interest expense		$ (786)
Other Comprehensive Income (Loss) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains (losses) recognized in other comprehensive income	$ (1,125)	$ (3,379)