Stockholders' Equity - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stockholders' Equity
Shares of common stock, authorized (shares)	600,000,000
Shares of common stock, issued and sold (shares)	143,433,099
Common Stock [Member]
Stockholders' Equity
Stock Issued During Period, Shares, New Issues	3,078,494	6,527,072