Loss and Loss Adjustment Expense Reserves (Tables)

6 Months Ended

Jun. 30, 2017

Loss and Loss Adjustment Expenses Reserves [Abstract]

Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block]

Activity in the loss and loss adjustment expense reserves is summarized as follows:

	June 30,
(millions)	2017		2016
Balance, Beginning of period	$	11,368.0	$	10,039.0
Less reinsurance recoverables on unpaid losses	1,801.0		1,442.7
Net balance, Beginning of period	9,567.0		8,596.3
Net loss and loss adjustment expense reserves disposed1	—		(2.5		)
Total beginning reserves	9,567.0		8,593.8
Incurred related to:
Current year	8,804.1		8,126.8
Prior years	74.2		29.6
Total incurred	8,878.3		8,156.4
Paid related to:
Current year	4,951.0		4,611.5
Prior years	3,381.8		3,059.8
Total paid	8,332.8		7,671.3
Net balance, End of period	10,112.5		9,078.9
Plus reinsurance recoverables on unpaid losses	1,947.9		1,595.9
Balance, End of period	$	12,060.4	$	10,674.8

¹ During 2016, $2.5 million net reserves were disposed by ARX in an exchange transaction.