General form of registration statement for all companies including face-amount certificate companies

Derivatives - Narrative (Details)

v3.19.3.a.u2
Derivatives - Narrative (Details)
1 Months Ended 8 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2019
USD ($)
Aug. 31, 2019
USD ($)
Sep. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
interest_rate_swap
Dec. 31, 2017
USD ($)
interest_rate_swap
Dec. 31, 2016
USD ($)
Derivative [Line Items]            
Derivative amount not offset against collateral       $ 0 $ 0  
Unrealized loss on derivative financial instruments, net $ 0 $ 4,577,000 $ 0 3,151,000 0 $ 0
Recurring            
Derivative [Line Items]            
Derivative asset 0 [1]     10,552,000 [1] 7,058,000  
Derivative liability 0 [1]     6,039,000 [1] 13,817,000  
Level 2 | Recurring            
Derivative [Line Items]            
Derivative asset 0 [1]     10,552,000 [1] $ 7,058,000  
Number of instruments held | interest_rate_swap         6  
Derivative liability $ 0 [1]     6,039,000 [1] $ 13,817,000  
Interest Rate Swap | Cash flow hedge            
Derivative [Line Items]            
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net       $ 1,890,000    
Interest Rate Swap | Level 2 | Recurring            
Derivative [Line Items]            
Number of derivative instruments held | interest_rate_swap       2 2  
Derivative asset       $ 10,552,000 $ 7,058,000  
Number of instruments held | interest_rate_swap       2    
Derivative liability       $ 6,039,000    
[1] Swap asset values are included in non-current Other assets and Swap liability values are included in non-current Derivative financial instruments on the condensed consolidated balance sheets.