Share Repurchase Programs - Additional Information (Detail) - USD ($)		1 Months Ended	2 Months Ended	3 Months Ended		7 Months Ended	12 Months Ended	20 Months Ended
	Feb. 13, 2015	Aug. 31, 2014	Feb. 19, 2016	Mar. 31, 2016	Mar. 31, 2015	Feb. 28, 2015	Dec. 31, 2015	Mar. 31, 2016	Feb. 20, 2015	Aug. 06, 2014
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased, shares				689,944			2,751,454	9,793,246
Amount paid to counter party under share repurchase program				$ 24,826,000	$ 12,352,000
Share repurchase, weighted average price				$ 35.98				$ 34.07
Common stock repurchased, value				$ 24,826,000
Share repurchase, remaining amount authorized							$ 91,261,000
ASR Program [Member]
Equity, Class of Treasury Stock [Line Items]
Percentage of common shares initially delivered under share repurchase program										80.00%
Amount paid to counter party under share repurchase program		$ 200,000,000
Share repurchase, weighted average price				$ 31.49
ASR Program [Member] | Maximum [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase, amount authorized										$ 200,000,000
ASR Program [Member] | JP Morgan Securities LLC [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase, amount authorized										$ 200,000,000
Common stock repurchased, shares	784,694	5,567,154				6,351,848
New Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase, amount authorized									$ 200,000,000
Common stock repurchased, shares			497,094
Share repurchase, weighted average price			$ 35.45				$ 39.55
Common stock repurchased, value			$ 17,622,000				$ 108,821,000
Amended Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase, amount authorized			200,000,000
Common stock repurchased, shares				192,850
Share repurchase, weighted average price				$ 37.35
Common stock repurchased, value				$ 7,204,000
Share repurchase, remaining amount authorized			$ 73,654,000	$ 192,802,000				$ 192,802,000
Share repurchase, period description				February 22, 2016 through December 31, 2017