Derivative Instruments And Hedging Activities Notional Contracts by Derivative Type (Details) (USD $)	Mar. 31, 2015
economic hedges by derivative type [Line Items]
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss) before Taxes	$ 3,000,000
Commodity Contract [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	6,232,000
Natural Gas Liquids [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	1,350,000
Natural Gas - long [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	26,400,000
Natural Gas - Short [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	26,400,000
Commodity WTI short [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	564,000
Maturing in Next Twelve Months [Member] | Commodity Contract [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	5,500,000
Maturing in Next Twelve Months [Member] | Natural Gas Liquids [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	1,350,000
Maturing in Next Twelve Months [Member] | Natural Gas - long [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	7,200,000
Maturing in Next Twelve Months [Member] | Natural Gas - Short [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	7,200,000
Maturing in Next Twelve Months [Member] | Commodity WTI short [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	564,000
Maturing in Year Three [Member] | Natural Gas - long [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	9,600,000
Maturing in Year Three [Member] | Natural Gas - Short [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	9,600,000
Maturing in Year Two [Member] | Commodity Contract [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	732,000
Maturing in Year Two [Member] | Natural Gas - long [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	9,600,000
Maturing in Year Two [Member] | Natural Gas - Short [Member]
economic hedges by derivative type [Line Items]
Economic Hedges Notional Contract Volumes	$ 9,600,000