XML 101 R74.htm IDEA: XBRL DOCUMENT v3.2.0.727
Debt - Additional Information (Detail) - USD ($)
$ in Thousands
Jun. 30, 2015
Dec. 31, 2014
Debt Instrument [Line Items]    
Outstanding amount of margin borrowing facility $ 187,407 $ 174,673
Margin borrowing facilities    
Debt Instrument [Line Items]    
Stated interest rate 1.00%  
Collateral deposited to support borrowing $ 238,300