Commitments and Contingencies (Details) (USD $)	3 Months Ended	36 Months Ended
	Mar. 31, 2013 item	Mar. 31, 2013
Restricted shares
Employment contracts
Vesting period	4 years
Petrello
Employment contracts
Initial term of the employment agreement	5 years
Automatic extension period	1 year
New term of the employment agreement	90 days
Base salary	$ 1,700,000
Amount of cash incentives awarded	18,000,000
Amount credited under the Executive Deferred Compensation Plan ("Executive Plan")	300,000	250,000
Employment benefit due to death or disability, payment period	30 days
Employment agreement termination without cause, benefit as a ratio to 3 year average base salary and bonus through March 30, 2015	2.99
Employment agreement termination without cause, benefit base period	3 years
Employment agreement amount of group life insurance multiplier of base salary	3
Petrello | TSR Shares
Employment contracts
Vesting period	3 years
Value of award that will vest as percentage of base salary	150.00%
Petrello | Performance Shares
Employment contracts
Vesting period	3 years
Value of award that will vest as percentage of base salary	200.00%
Petrello | Common stock
Employment contracts
Value of incentives in the form of one-time stock grant	27,000,000
Petrello | Restricted shares
Employment contracts
Value of incentives in the form of one-time award	$ 15,000,000