Receivables (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Accounts Receivable Sold [Line Items]
Receivables (sold) purchased	$ 0		$ 0
Gain (Loss) on Sale of Accounts Receivable	(0.2)	[1]	(0.9)	[1]
Servicing fees received (paid)	0		0
Fees paid to outside investor	(1.9)		(1.7)
Cash from customers (transferred) received	0		0
Cash received from (paid for) receivables purchased	0		0
Intercompany Interest Income (Expense) On Notes	0		0
Kansas City Power and Light Company [Member]
Accounts Receivable Sold [Line Items]
Receivables (sold) purchased	0		0
Gain (Loss) on Sale of Accounts Receivable	(0.1)	[1]	0.1	[1]
Servicing fees received (paid)	0		0
Fees paid to outside investor	(1.2)		(1.2)
Cash from customers (transferred) received	0		0
Cash received from (paid for) receivables purchased	0		0
Intercompany Interest Income (Expense) On Notes	0		0
Kansas City Power And Light Company Unconsolidated [Member]
Accounts Receivable Sold [Line Items]
Receivables (sold) purchased	(1,517.2)		(1,436.0)
Gain (Loss) on Sale of Accounts Receivable	(19.2)	[1]	(18.2)	[1]
Servicing fees received (paid)	2.6		2.5
Fees paid to outside investor	0		0
Cash from customers (transferred) received	(1,516.2)		(1,452.4)
Cash received from (paid for) receivables purchased	1,497.2		1,434.2
Intercompany Interest Income (Expense) On Notes	0.3		0.3
KCPL Receivables Company [Member]
Accounts Receivable Sold [Line Items]
Receivables (sold) purchased	1,517.2		1,436.0
Gain (Loss) on Sale of Accounts Receivable	19.1	[1]	18.3	[1]
Servicing fees received (paid)	(2.6)		(2.5)
Fees paid to outside investor	(1.2)		(1.2)
Cash from customers (transferred) received	1,516.2		1,452.4
Cash received from (paid for) receivables purchased	(1,497.2)		(1,434.2)
Intercompany Interest Income (Expense) On Notes	(0.3)		(0.3)
KCPL Greater Missouri Operations [Member]
Accounts Receivable Sold [Line Items]
Receivables (sold) purchased	(834.7)		(597.8)
Gain (Loss) on Sale of Accounts Receivable	(10.6)	[1]	(7.6)	[1]
Servicing fees received (paid)	1.4		0.9
Fees paid to outside investor	0		0
Cash from customers (transferred) received	(830.9)		(524.0)
Cash received from (paid for) receivables purchased	820.5		517.5
Intercompany Interest Income (Expense) On Notes	0.1		0.1
GMO Receivables Company Member
Accounts Receivable Sold [Line Items]
Receivables (sold) purchased	834.7		597.8
Gain (Loss) on Sale of Accounts Receivable	10.5	[1]	6.6	[1]
Servicing fees received (paid)	(1.4)		(0.9)
Fees paid to outside investor	(0.7)		(0.5)
Cash from customers (transferred) received	830.9		524.0
Cash received from (paid for) receivables purchased	(820.5)		(517.5)
Intercompany Interest Income (Expense) On Notes	$ (0.1)		$ (0.1)

[1] Any net gain (loss) is the result of the timing difference inherent in collecting receivables and over the life of the agreement will net to zero.