Long-Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2011 4.625% Notes due July 15, 2013		Dec. 31, 2010 4.625% Notes due July 15, 2013		Dec. 31, 2011 5.300% Notes due October 15, 2014		Dec. 31, 2010 5.300% Notes due October 15, 2014		Dec. 31, 2011 5.125% Notes due July 1, 2017		Dec. 31, 2010 5.125% Notes due July 1, 2017		Dec. 31, 2011 6.050% Notes due January 15, 2018		Dec. 31, 2010 6.050% Notes due January 15, 2018		Dec. 31, 2011 5.500% Notes due August 15, 2019		Dec. 31, 2010 5.500% Notes due August 15, 2019		Dec. 31, 2011 4.875% Notes due February 1, 2021		Jan. 13, 2011 4.875% Notes due February 1, 2021	Dec. 31, 2011 6.750% Notes due August 15, 2033		Dec. 31, 2010 6.750% Notes due August 15, 2033		Dec. 31, 2011 Credit Facility		Dec. 31, 2010 Credit Facility		Dec. 31, 2010 BES Credit Facility	Dec. 31, 2010 Services Company 3.60% ESOP Notes due March 28, 2011
Debt Instrument [Line Items]
Retirement premium			$ (6)
Notes Payable	2,650,200		1,808,825		300,000	[1]	300,000	[1]	275,000	[1]	275,000	[1]	125,000	[1]	125,000	[1]	300,000	[1]	300,000	[1]	275,000	[1]	275,000	[1]	650,000	[1]	650,000	150,000	[1]	150,000	[1]						1,531
Other, including unamortized discounts	(5,426)		(3,607)
Subtotal debt	2,644,774		1,805,218
Less: Current portion of long-term debt and line of credit	(251,200)	[2]	(285,825)	[2]
Total long-term debt	2,393,574		1,519,393
Credit facility, amount outstanding																																$ 575,200	[3]	$ 98,000	[3]	$ 284,300

[1] We make semi-annual interest payments on these notes based on the rates noted above with the principal balances outstanding to be paid on or before the due dates as shown above.

[2] The line of credit is classified as a current liability in our consolidated balance sheets as related funds are used to finance BES's current working capital needs.

[3] Includes the Credit Facility and Prior BPL Credit Facility as defined below.