Annual report pursuant to Section 13 and 15(d)

Quarterly Financial Data (Unaudited) (Narrative) (Detail)

v3.19.1
Quarterly Financial Data (Unaudited) (Narrative) (Detail) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Schedule of Quarterly Financial Information [Line Items]                      
Expenses $ 342,060 $ 336,164 $ 343,822 $ 321,687 $ 344,095 $ 317,649 $ 310,286 $ 294,961 $ 1,343,733 $ 1,266,991 $ 1,119,023
Non Cash Compensation                      
Schedule of Quarterly Financial Information [Line Items]                      
Expenses $ 1,440 $ 1,380 $ 1,568 $ 1,494 $ 1,391 $ 1,341 $ 1,378 $ 1,429