Securities Financing Including Redeemable Preferred Stocks - Additional Information (Detail) - shares	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Series E Redeemable Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock cumulative dividend rate	14.00%
Participating right in dividends and liquidating distributions expressed in number of common shares	303,646
Redeemable preferred stock, shares outstanding	139,768	139,768
Series F Redeemable Preferred Stock [Member]
Class Of Stock [Line Items]
Redeemable preferred stock, shares outstanding	1
Common stock voting rights shares	456,225
Voting rights description	As of March 31, 2017, the one share of Series F Redeemable Preferred has voting rights (the “Series F Voting Rights”) to vote as a single class on all matters which the common stock have the right to vote and is entitled to a number of votes equal to 456,225 shares of our common stock.