Property Casualty Loss and Loss Expenses

This table summarizes activity for our consolidated property casualty loss and loss expense reserves:



(Dollars in millions)	Three months ended March 31,
	2018			2017
Gross loss and loss expense reserves, beginning of period	$	5,219		$	5,035
Less reinsurance recoverable	187			298
Net loss and loss expense reserves, beginning of period	5,032			4,737
Net incurred loss and loss expenses related to:
Current accident year	839			826
Prior accident years	(48		)	(38		)
Total incurred	791			788
Net paid loss and loss expenses related to:
Current accident year	195			185
Prior accident years	519			509
Total paid	714			694
Net loss and loss expense reserves, end of period	5,109			4,831
Plus reinsurance recoverable	184			297
Gross loss and loss expense reserves, end of period	$	5,293		$	5,128

We use actuarial methods, models and judgment to estimate, as of a financial statement date, the property casualty loss and loss expense reserves required to pay for and settle all outstanding insured claims, including incurred but not reported (IBNR) claims, as of that date. The actuarial estimate is subject to review and adjustment by an inter-departmental committee that includes actuarial, claims, underwriting, loss prevention and accounting management. This committee is familiar with relevant company and industry business, claims and underwriting trends, as well as general economic and legal trends that could affect future loss and loss expense payments. The amount we will actually have to pay for claims can be highly uncertain. This uncertainty, together with the size of our reserves, makes the loss and loss expense reserves our most significant estimate. The reserve for loss and loss expenses in the condensed consolidated balance sheets also included $52 million at March 31, 2018, and

$49 million at March 31, 2017, for certain life and health loss and loss expense reserves.

For the three months ended March 31, 2018, we experienced $48 million of favorable development on prior accident years, including $35 million of favorable development in commercial lines, $1 million of favorable development in personal lines, $10 million of favorable development in excess and surplus lines and $2 million of favorable development in our reinsurance assumed operations. This included $7 million from favorable development of catastrophe losses for the three months ended March 31, 2018. For the three months ended March 31, 2018, we recognized favorable reserve development of $21 million for the commercial property line, $13 million for the workers' compensation line, $2 million for the commercial auto line and $4 million for the other commercial lines due to reduced uncertainty of prior accident year loss and loss adjustment expense for these lines. For the three months ended March 31, 2018, we recognized unfavorable reserve development of $5 million for the commercial casualty line. The unfavorable reserve development for commercial casualty was primarily due to an increase in case reserves for accident year 2017.

For the three months ended March 31, 2017, we experienced $38 million of favorable development on prior accident years, including $11 million of favorable development in commercial lines, $10 million of favorable development in personal lines, $13 million of favorable development in excess and surplus lines and $4 million of favorable development in our reinsurance assumed operations. This included $11 million from favorable development of catastrophe losses for the three months ended March 31, 2017. For the three months ended March 31, 2017, we recognized favorable reserve development of $18 million for the workers' compensation line, $10 million for the commercial property line and $8 million for the other commercial lines due to reduced uncertainty of prior accident year loss and loss adjustment expenses for these lines. For the three months ended March 31, 2017, we recognized unfavorable reserve development of $15 million for the commercial casualty line and $10 million for the commercial auto line. The unfavorable reserve development for commercial casualty reflected higher than usual large loss activity. Commercial auto developed unfavorably due to higher loss cost effects in recent accident years, resulting in an increase of our reserve estimate for claims that have not yet been settled.