Net Income (Loss) Per Share (Tables)

12 Months Ended

Dec. 31, 2015

Earnings Per Share [Abstract]

Basic and Diluted Net Income (Loss) Per Share

The calculations of basic and diluted net income per share are as follows:

	Year Ended December 31,
	2015		2014		2013
Net income - basic and diluted	$	636,056	$	338,126	$	413,738
(Shares in thousands)
Weighted average shares - basic	103,061		100,612		97,917
Effect of dilutive securities:
Stock options	9,446		9,440		10,233
Restricted stock	477		425		433
Warrants	2,246		2,936		2,707
Dilutive potential shares	12,169		12,801		13,373
Weighted average shares - diluted	115,230		113,413		111,290
Net income per share - basic	$	6.17	$	3.36	$	4.23
Net income per share - diluted	$	5.52	$	2.98	$	3.72

Antidilutive Securities

Shares which have been excluded from diluted per share amounts because their effect would have been antidilutive, include the following:

	Year Ended December 31,
(Shares in thousands)	2015	2014	2013
Stock options	1,343	1,470	304
Convertible senior notes	994	4,247	4,761