Consolidated Statements of Cash Flows - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014
Statement of Cash Flows [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 664.1	$ 614.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation		49.7	46.7
Amortization of intangible assets		15.7	0.0
Amortization of fixed-income securities		43.5	38.1
Amortization of equity-based compensation		26.5	29.8
Net realized (gains) losses on securities		(109.0)	(159.8)
Net (gains) losses on disposition of property and equipment		0.7	3.3
Changes in:
Premiums receivable		(300.5)	(255.4)
Reinsurance recoverables		(116.1)	(44.8)
Prepaid reinsurance premiums		(1.2)	(14.9)
Deferred acquisition costs		(46.4)	(31.4)
Income taxes		(82.9)	53.6
Unearned premiums		652.0	407.7
Loss and loss adjustment expense reserves		537.7	160.1
Accounts payable, accrued expenses, and other liabilities		66.9	164.0
Other, net		29.3	29.5
Net cash provided by operating activities		1,430.0	1,041.2
Purchases:
Fixed maturities		(5,316.7)	(3,332.1)
Equity securities		(257.2)	(176.7)
Sales:
Fixed maturities		2,780.0	3,329.3
Equity securities		200.4	446.4
Maturities, paydowns, calls, and other:
Fixed maturities		1,595.1	1,117.8
Equity securities		12.0	14.2
Net sales (purchases) of short-term investments		523.4	(1,846.0)
Net unsettled security transactions		128.4	174.5
Purchases of property and equipment		(53.6)	(44.7)
Payments to Acquire Businesses, Net of Cash Acquired		(752.7)	0.0
Payments to Acquire Additional Interest in Subsidiaries		(12.6)	0.0
Sales of property and equipment		7.1	3.1
Net cash used in investing activities		(1,146.4)	(314.2)
Cash Flows From Financing Activities
Tax benefit from vesting of equity-based compensation		8.7	10.7
Proceeds from debt issuance		382.0	344.7
Dividends paid to shareholders	[1]	(403.6)	(892.6)
Acquisition of treasury shares		(108.1)	(140.0)
Net cash used in financing activities		(127.8)	(677.2)
Repayments of Debt		6.8	0.0
Effect of exchange rate changes on cash		(0.4)	1.2
Increase in cash		155.4	51.0
Cash, Beginning of year		108.4	75.1
Cash, End of period		263.8	126.1
Early Repayment of Subordinated Debt		$ 0.0	$ 0.0

[1] Progressive maintains an annual dividend program. See Note 8 - Dividends for further discussion.See notes to consolidated financial statements.