Stockholders' Equity - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 01, 2015	Apr. 30, 2014	Dec. 31, 2014	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Aug. 12, 2014
Stockholders Equity [Line Items]
Common stock, shares issued			90,191,100		90,303,587
Unvested shares of common stock					4,009,725
Number of shares repurchased			4,105,970		4,105,970
Dividends declared to common stockholders					$ 54,482,000
Dividends payable			$ 172,000		$ 18,391,000
Secondary offering costs				$ 73,000		$ 747,000
Share Repurchase Program, authorized amount							$ 250,000,000
Shares repurchased			855,970
Stock repurchased during period under Share Repurchase Program, average price per share			$ 17.50
Share Repurchase Program, remaining authorized repurchase amount			$ 235,000,000		$ 235,000,000
Stock repurchased during period, total cost			15,000,000
Shares repurchased payment settlement during period					5,650,000	$ 50,706,000
Treasury stock at cost			$ 109,871,000		$ 109,871,000
Subsequent Event [Member]
Stockholders Equity [Line Items]
Dividends paid	$ 18,100,000
2.25x Performance Restricted Shares [Member]
Stockholders Equity [Line Items]
Unvested shares of common stock			1,451,453		1,373,662
Dividends payable on unvested restricted performance shares not probable of vesting					$ 2,540,000
2.75x Performance Restricted Shares [Member]
Stockholders Equity [Line Items]
Unvested shares of common stock			1,451,453		1,373,662
Dividends payable on unvested restricted performance shares not probable of vesting					$ 2,540,000
Bonus Performance Restricted Shares [Member]
Stockholders Equity [Line Items]
Unvested shares of common stock					433,463
Dividends payable on unvested restricted performance shares not probable of vesting					$ 177,000
Long-Term Incentive Performance Restricted Shares [Member]
Stockholders Equity [Line Items]
Unvested shares of common stock					67,487
Dividends payable on unvested restricted performance shares not probable of vesting					$ 28,000
Dividends on shares probable of vesting					9,000
Secondary Offering [Member]
Stockholders Equity [Line Items]
Common stock, shares issued		0
Number of shares repurchased		1,750,000
Shares offered and sold by the selling stockholders		17,250,000
Treasury stock at cost			$ 109,871,000		$ 109,871,000