CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
OPERATING ACTIVITIES
Net income	$ 156.0	$ 73.8
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	199.2	190.8
Deferred income taxes	69.1	40.0
Abandonment and impairment	6.6	5.4
Share-based compensation	5.7	7.4
Amortization of debt issuance costs and discounts	1.1	0.8
Dry exploratory well expense	0.1	0.6
Net gain from asset sales	(1.5)	0
Income from unconsolidated affiliates	(1.9)	(0.9)
Distributions from unconsolidated affiliates and other	1.6	1.8
Unrealized gain on derivative contracts	(128.3)	(31.2)
Changes in operating assets and liabilities	20.8	10.9
Net Cash Provided by Operating Activities	328.5	299.4
INVESTING ACTIVITIES
Property acquisitions	(1.4)	(22.1)
Property, plant and equipment, including dry exploratory well expense	(336.5)	(320.4)
Proceeds from disposition of assets	3.3	0.9
Net Cash Used in Investing Activities	(334.6)	(341.6)
FINANCING ACTIVITIES
Checks outstanding in excess of cash balances	29.2	5.9
Long-term debt issued	500.0	0
Long-term debt issuance costs paid	(6.9)	0
Current portion long-term debt repaid	0	(58.5)
Proceeds from credit facility	120.0	200.0
Repayments of credit facility	(626.0)	(100.0)
Other capital contributions	(6.9)	(0.8)
Dividends paid	(3.6)	(3.5)
Excess tax benefit on share-based compensation	2.0	0.4
Distribution from Questar	0	0.2
Distribution to noncontrolling interest	(1.7)	(1.5)
Net Cash Provided by Financing Activities	6.1	42.2
Change in cash and cash equivalents	0	0
Beginning cash and cash equivalents	0	0
Ending cash and cash equivalents	0	0
Supplemental Disclosures:
Cash paid for interest	39.6	44.2
Cash paid (received) for income taxes	(2.6)	(10.8)
Increase (decrease) in non-cash capital expenditure accruals	$ 3.5	$ (27.7)