Shareholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		7 Months Ended	12 Months Ended
	May. 31, 2015	Oct. 31, 2012	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Oct. 31, 2015	Mar. 31, 2015	Jun. 10, 2014
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Proceeds from the issuance of preferred stock, net		$ 110,300		$ 0	$ 313,330	$ 0
Preferred stock liquidation preference (in dollars per share)			$ 10,000	$ 10,000	$ 10,000
Premium for conversion price to concurrent common stock offering price				2000.00%
Common stock offering price, new issue (in dollars per share)							$ 5.00
Conversion ratio into common stock if closing sale price exceed prior period conversion price				130.00%
Preferred Stock, Amount of Preferred Dividends in Arrears				$ 10,700
Common Stock, Shares Authorized, Increase During Period	100,000,000
Common stock, shares authorized			128,000,000	228,000,000	128,000,000			128,000,000
Proceeds from Issuance of Convertible Preferred Stock				$ 313,300
Premium, Conversion Price to Common Share Closing Price Prior to Series B Preferred Stock Offering									30.00%
Common Share Price, Last Reported Prior to Series B Preferred Stock Offering									$ 14.11
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock Conversions, Inducements				0	$ 4,256	0
Accumulated other comprehensive losses attributable to pension and postretirement benefit obligations, net of tax			$ 200	$ 400	$ 200	$ 300
Treasury stock (in shares)			262,070	455,689	262,070
Series A Preferred Stock
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate				6.00%
Conversion price (in dollars per share)				$ 6.00
Preferred Stock, Amount of Preferred Dividends in Arrears				$ 1,700
Convertible Preferred Stock, Shares Issued upon Conversion				1,666.67
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Issuance of common stock (in shares)		11,500
Conversion of Stock, Shares Converted				4,029	3,555
Preferred Stock Conversions, Inducements					$ 4,300
Series B Preferred Stock
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate			6.00%	6.00%
Conversion price (in dollars per share)				$ 18.34
Preferred Stock, Amount of Preferred Dividends in Arrears				$ 9,000
Convertible Preferred Stock, Shares Issued upon Conversion				545.17
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Issuance of common stock (in shares)				32,500
Conversion of Stock, Shares Converted				4,949
Common Stock
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Stock Issued During Period, Shares, Conversion of Convertible Securities					5,900,000
Series A Preferred Stock Converted to Common [Member] [Member] | Common Stock
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Stock Issued During Period, Shares, Conversion of Convertible Securities				6,700,000
Series B Preferred Stock Converted to Common [Member] | Common Stock
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Stock Issued During Period, Shares, Conversion of Convertible Securities				2,700,000