Preferred Stock and Warrant - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2014
Class of Stock [Line Items]
Limitations on payment of dividends on common stock	no more than 100% of the aggregate per share dividend
Dividend declared and paid, common stock		$ 0.15	$ 0.15	$ 0.15
Preferred stock, issued	17,123				17,123
Series CD Preferred Stock
Class of Stock [Line Items]
Preferred stock, annual dividend rate	2.00%
Capital purchase liquidation dividend term	8 years