Annual report pursuant to Section 13 and 15(d)

Quarterly Financial Data (Unaudited) (Narrative) (Details)

v3.20.1
Quarterly Financial Data (Unaudited) (Narrative) (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Schedule of Quarterly Financial Information [Line Items]                      
Expenses $ 394,992 $ 359,142 $ 353,982 $ 330,515 $ 342,060 $ 336,164 $ 343,822 $ 321,687 $ 1,438,631 $ 1,343,733 $ 1,266,991
Non Cash Compensation                      
Schedule of Quarterly Financial Information [Line Items]                      
Expenses $ 1,632 $ 1,536 $ 1,444 $ 1,494 $ 1,440 $ 1,380 $ 1,568 $ 1,494