Quarterly Financial Information (Unaudited) - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Selected Quarterly Financial Information [Line Items]
Loss on extinguishment on debt			$ 2,100,000			$ 4,200,000			$ 2,148,000	$ 4,181,000
Loss on call spread modification related to convertible notes			5,000,000				4,900,000		5,417,000	4,869,000
(Provision) benefit for income taxes	1,096,000	463,000	(576,000)	484,000	12,136,000	12,450,000	1,784,000	66,292,000	1,467,000	92,662,000	2,034,000
REIT conversion costs										22,190,000	101,964,000
REIT Conversion Costs [Member]
Selected Quarterly Financial Information [Line Items]
REIT conversion costs							5,400,000	15,000,000
Peterson Companies [Member]
Selected Quarterly Financial Information [Line Items]
Bond issued, face value	26,100,000								26,100,000
Term of Peterson Note									3 years
REIT Conversion [Member]
Selected Quarterly Financial Information [Line Items]
(Provision) benefit for income taxes								$ 61,300,000		$ 64,800,000