Quarterly report pursuant to Section 13 or 15(d)

Fair Value Disclosures - Financial Assets and Liabilities Measured at Fair Value (Details)

v3.10.0.1
Fair Value Disclosures - Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Supplemental Employee Retirement Plan [Member]    
Assets:    
SERP $ 1,364 $ 1,858
Supplemental Employee Retirement Plan [Member] | Level 1    
Assets:    
SERP 0 0
Supplemental Employee Retirement Plan [Member] | Level 2    
Assets:    
SERP 1,364 1,858
Supplemental Employee Retirement Plan [Member] | Level 3    
Assets:    
SERP 0 0
Interest Rate Swap [Member]    
Assets:    
Interest rate swaps 17,181 9,419
Interest Rate Swap [Member] | Level 1    
Assets:    
Interest rate swaps 0 0
Interest Rate Swap [Member] | Level 2    
Assets:    
Interest rate swaps 17,181 9,419
Interest Rate Swap [Member] | Level 3    
Assets:    
Interest rate swaps $ 0 $ 0