Stockholders' Equity - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended			12 Months Ended
	Feb. 24, 2016	Jun. 30, 2015	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2015	Nov. 30, 2014
Class of Stock [Line Items]
Proceeds from common stock issuance, net		$ 717,800,000				$ 717,802,000
Common stock, shares authorized						200,000,000	100,000,000		200,000,000
Quarterly cash dividend paid	$ 0.125					$ 0.50	$ 0.125
Dividend paid date	Mar. 15, 2016
Dividend record date	Mar. 07, 2016
Dividends paid on common stock						$ 45,451,000	$ 10,494,000
Number of common stock shares repurchased			88,700	95,800	90,226	0	274,726	23,900
Repurchase of common stock						$ 0	$ 11,223,000	$ 943,000
Maximum [Member]
Class of Stock [Line Items]
Amount authorized for share repurchase program										$ 200,000,000
First Quarter Dividend [Member]
Class of Stock [Line Items]
Quarterly cash dividend paid						$ 0.125
Dividend paid date						Mar. 16, 2015
Dividend record date						Mar. 02, 2015
Second Quarter Dividend [Member]
Class of Stock [Line Items]
Quarterly cash dividend paid						$ 0.125
Dividend paid date						Jun. 15, 2015
Dividend record date						Jun. 01, 2015
Third Quarter Dividend [Member]
Class of Stock [Line Items]
Quarterly cash dividend paid						$ 0.125
Dividend paid date						Sep. 15, 2015
Dividend record date						Sep. 01, 2015
Fourth Quarter Dividend [Member]
Class of Stock [Line Items]
Dividend paid date						Dec. 15, 2015
Dividend record date						Dec. 01, 2015
Common Stock [Member]
Class of Stock [Line Items]
Common stock shares issued		12,075,000				12,077,000		25,000
Common stock offering price		$ 61.50
Common Stock [Member] | Underwriters' Option [Member]
Class of Stock [Line Items]
Common stock shares issued		1,575,000