Net Income per Share (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Nov. 22, 2016	Nov. 20, 2015	Feb. 12, 2014
Restricted Stock [Member]
Debt Instrument [Line Items]
Antidilutive securities excluded from computation of earnings per share (in Shares)	1,819,388	1,154,000	1,911,828	1,095,000
Option on Securities [Member]
Debt Instrument [Line Items]
Antidilutive securities excluded from computation of earnings per share (in Shares)	126,000	0	59,000	0
February 2018 Notes [Member]
Debt Instrument [Line Items]
Convertible notes	$ 124,922		$ 124,922		$ 121,595	$ 126,400	$ 246,400	$ 300,000
February 2018 Notes [Member] | Warrants [Member]
Debt Instrument [Line Items]
Antidilutive securities excluded from computation of earnings per share (in Shares)	12,200,000	23,800,000
February 2018 Notes [Member] | Purchased Call Options [Member]
Debt Instrument [Line Items]
Antidilutive securities excluded from computation of earnings per share (in Shares)	13,800,000	26,900,000
December 2021 Notes [Member]
Debt Instrument [Line Items]
Convertible notes	$ 115,716		$ 115,716		$ 110,848	$ 150,000	$ 150,000