Statements of Consolidated Balance Sheets - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment
Plant		$ 24,524.7	$ 24,179.9
Accumulated depreciation and amortization		(7,688.0)	(7,560.4)
Net Property, Plant and Equipment	[1]	16,836.7	16,619.5
Investments and Other Assets
Available-for-sale debt securities (amortized cost of $163.8 and $163.9, allowance for credit losses of $0.3 and $0.5, respectively)		167.9	170.9
Other investments		81.5	81.1
Total Investments and Other Assets		249.4	252.0
Current Assets
Cash and cash equivalents		89.1	116.5
Restricted Cash		7.6	9.1
Accounts receivable		848.4	843.6
Allowance for credit losses		(53.9)	(52.3)
Accounts receivable, net		794.5	791.3
Gas inventory		48.1	191.2
Materials and supplies, at average cost		145.6	141.5
Electric production fuel, at average cost		52.5	68.4
Exchange gas receivable		53.7	34.1
Regulatory assets		188.9	135.7
Deferred property taxes		104.2	85.6
Prepayments and other		109.3	86.0
Total Current Assets	[1]	1,593.5	1,659.4
Other Assets
Regulatory assets		1,791.3	1,794.8
Goodwill		1,485.9	1,485.9
Deferred charges and other		237.7	228.9
Total Other Assets		3,514.9	3,509.6
Total Assets		22,194.5	22,040.5
Stockholders' Equity
Common stock - $0.01 par value, 600,000,000 shares authorized; 392,129,866 and 391,760,051 shares outstanding, respectively		3.9	3.9
Preferred stock - $0.01 par value, 20,000,000 shares authorized; 440,000 shares outstanding		880.0	880.0
Treasury stock		(99.9)	(99.9)
Additional paid-in capital		6,892.9	6,890.1
Retained deficit		(1,669.8)	(1,765.2)
Accumulated other comprehensive loss		(75.5)	(156.7)
Total NiSource Stockholders’ Equity		5,931.6	5,752.2
Noncontrolling interest in consolidated subsidiaries		94.1	85.6
Total Stockholders' Equity		6,025.7	5,837.8
Long-term debt, excluding amounts due within one year		9,202.3	9,219.8
Total Capitalization		15,228.0	15,057.6
Current Liabilities
Current portion of long-term debt		44.4	23.3
Short-term borrowings		520.0	503.0
Accounts payable		554.9	589.0
Dividends payable - common stock		86.3	0.0
Dividends payable - preferred stock		19.4	0.0
Customer deposits and credits		146.7	243.3
Taxes accrued		301.5	244.1
Interest accrued		94.6	104.7
Exchange gas payable		25.5	48.5
Regulatory liabilities		169.6	161.3
Accrued compensation and employee benefits		131.2	141.8
Other accruals		164.7	220.4
Total Current Liabilities		2,258.8	2,279.4
Other Liabilities
Deferred income taxes		1,573.6	1,470.6
Accrued liability for postretirement and postemployment benefits		328.9	336.1
Regulatory liabilities		1,881.0	1,904.2
Asset retirement obligations		479.7	477.1
Other noncurrent liabilities		444.5	515.5
Total Other Liabilities		4,707.7	4,703.5
Total Capitalization and Liabilities		$ 22,194.5	$ 22,040.5

[1] (1)Includes $174.2 million and $175.6 million of net property, plant and equipment assets and $4.2 million and $1.7 million of current assets of a consolidated VIE as of March 31, 2021 and December 31, 2020 that may be used only to settle obligations of the consolidated VIE. Refer to Note 15 "Variable Interest Entities" for additional information.