Annual report pursuant to Section 13 and 15(d)

Equity - Summary of Dividends Declared by Board of Directors (Detail)

v3.8.0.1
Equity - Summary of Dividends Declared by Board of Directors (Detail) - $ / shares
 12 Months Ended
Jan. 11, 2018
Oct. 16, 2017
Jul. 13, 2017
Apr. 13, 2017
Jan. 12, 2017
Oct. 13, 2016
Jul. 14, 2016
Apr. 07, 2016
Dec. 31, 2017
3/30/2016 Record Date [Member]                  
Dividends Payable [Line Items]                  
Announced Date                 Mar. 15, 2016
Record Date                 Mar. 30, 2016
Pay Date                 Apr. 07, 2016
Amount per share               $ 0.30  
07/06/16 Record Date [Member]                  
Dividends Payable [Line Items]                  
Announced Date                 Jun. 07, 2016
Record Date                 Jul. 06, 2016
Pay Date                 Jul. 14, 2016
Amount per share             $ 0.30    
10/05/16 Record Date [Member]                  
Dividends Payable [Line Items]                  
Announced Date                 Sep. 15, 2016
Record Date                 Oct. 05, 2016
Pay Date                 Oct. 13, 2016
Amount per share           $ 0.30      
12/29/16 Record Date [Member]                  
Dividends Payable [Line Items]                  
Announced Date                 Dec. 13, 2016
Record Date [1]                 Dec. 29, 2016
Pay Date                 Jan. 12, 2017
Amount per share         $ 0.33        
4/05/2017 Record Date [Member]                  
Dividends Payable [Line Items]                  
Announced Date                 Mar. 15, 2017
Record Date                 Apr. 05, 2017
Pay Date                 Apr. 13, 2017
Amount per share       $ 0.33          
7/06/2017 Record Date [Member]                  
Dividends Payable [Line Items]                  
Announced Date                 Jun. 01, 2017
Record Date                 Jul. 06, 2017
Pay Date                 Jul. 13, 2017
Amount per share     $ 0.33            
10/05/2017 Record Date [Member]                  
Dividends Payable [Line Items]                  
Announced Date                 Sep. 12, 2017
Record Date                 Oct. 05, 2017
Pay Date                 Oct. 16, 2017
Amount per share   $ 0.33              
12/12/17 Record Date [Member]                  
Dividends Payable [Line Items]                  
Announced Date                 Dec. 12, 2017
Record Date [1]                 Dec. 26, 2017
Pay Date                 Jan. 11, 2018
Amount per share $ 0.33                
[1] These dividends are treated as distributions in the following year for tax purposes.