Stockholders' Equity - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended
	Nov. 14, 2013	Nov. 01, 2013
Stockholders' Equity [Line Items]
Public offering, common stock		4,693,876
Common stock per share price		$ 12.25
Net proceeds from stock offerings	$ 161,316
Series E [Member]
Stockholders' Equity [Line Items]
Public offering, depositary shares		4,000,000
Depositary shares, price per share		$ 25.00
Common Stock Over-Allotment Option [Member]
Stockholders' Equity [Line Items]
Public offering, common stock		612,244
Preferred Stock Over-Allotment Option [Member]
Stockholders' Equity [Line Items]
Public offering, depositary shares	435,080