XML 75 R63.htm IDEA: XBRL DOCUMENT v3.8.0.1
Junior Subordinated Debentures - Schedule of Maybrooke Junior Subordinated Debentures (Detail) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Debt Instrument [Line Items]    
Principal $ 143.8 $ 143.8
Maybrooke Junior Subordinated Debentures [Member]    
Debt Instrument [Line Items]    
Issue Date Sep. 15, 2007 Sep. 15, 2007
Maturity Sep. 15, 2037 Sep. 15, 2037
Rate Structure 3M LIBOR + 3.15%  
Interest Rate 5.27% 4.74%
Principal $ 91.8 $ 91.8
Carrying Value $ 83.9 $ 83.9