Reserve for Loss and Loss Expense

The table below provides a roll forward of reserve for loss and loss expense balances:



	Six Months ended June 30,
($ in thousands)	2018			2017
Gross reserve for loss and loss expense, at beginning of year	$	3,771,240		3,691,719
Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of year	585,855			611,200
Net reserve for loss and loss expense, at beginning of year	3,185,385			3,080,519
Incurred loss and loss expense for claims occurring in the:
Current year	756,855			684,877
Prior years	(5,586		)	(25,846	)
Total incurred loss and loss expense	751,269			659,031
Paid loss and loss expense for claims occurring in the:
Current year	214,169			171,724
Prior years	457,441			425,521
Total paid loss and loss expense	671,610			597,245
Net reserve for loss and loss expense, at end of period	3,265,044			3,142,305
Add: Reinsurance recoverable on unpaid loss and loss expense, at end of period	539,321			588,916
Gross reserve for loss and loss expense at end of period	$	3,804,365		3,731,221

The $72.0 million increase in current year loss and loss expense incurred illustrated in the table above was primarily driven by non-catastrophe property losses, as well as an increase in exposure due to premium growth. Non-catastrophe property losses, which increased $44.0 million, to $188.7 million, in Six Months 2018, were principally related to the early January deep freeze in our footprint states and a relatively large number of severe fire losses.

Prior year development in Six Months 2018 of $5.6 million included $12.0 million of favorable casualty development partially offset by $6.4 million of unfavorable property development. The favorable casualty development included $33.0 million of development in our workers compensation line of business, partially offset by unfavorable development of $15.0 million in our commercial automobile line of business and $6.0 million in our excess and surplus ("E&S") casualty lines.

Prior year development in Six Months 2017 of $25.8 million was primarily driven by favorable prior year casualty reserve development of $37.4 million in our general liability line of business and $15.3 million in our workers compensation line of business. This was partially offset by unfavorable development of $21.0 million in our commercial automobile line of business and $4.0 million in our personal automobile line of business.

For a discussion of the trends and recent developments impacting these lines, refer to the "Critical Accounting Policies and Estimates" section of Item 7. "Management's Discussion and Analysis of Financial Condition and Results of Operations." in our 2017 Annual Report.