Summary Of Significant Accounting Policies (Computations Of Basic And Diluted EPS) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary Of Significant Accounting Policies [Abstract]
Net income (loss) applicable to Helix	$ 7,960	$ 75,586	$ 57,782	$ 53,719	$ 36,503	$ 44,593	$ 27,211	$ 1,615	$ 195,047	$ 109,922	$ (46,334)
Income from discontinued operations, net of tax						(44)	29	(1,058)		(1,073)	(23,684)
Net income from continuing operations					36,503	44,549	27,240	557	195,047	108,849	(70,018)
Less: Undistributed net income allocable to participating securities									(1,018)	(801)
Net income applicable to common shareholders - continuing operations									194,029	108,048	(70,018)
Less: Undistributed net income from discontinued operations allocable to participating securities										(8)
Net income applicable to common shareholders - discontinued operations										1,065	23,684
Weighted average number of shares outstanding - basic									105,029	105,032	104,449
Share-based awards other than participating securities, shares									16	152
Undistributed earnings reallocated to participating securities, value										1
Net income applicable to Helix - Diluted									194,029	108,049	(70,018)
Weighted average number of shares outstanding, diluted									105,045	105,184	104,449
Income from discontinued operations, net of tax						$ 44	$ (29)	$ 1,058		$ 1,073	$ 23,684