Equity - Additional Information (Detail) - $ / shares	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Equity [Abstract]
Dividends declared per common share (in usd per share)	$ 0.16	$ 0.16	$ 0	$ 0.32	$ 0	$ 0.125
Dividend, payable date				Apr. 15, 2015
Dividend, record date				Mar. 31, 2015