PROPERTY AND EQUIPMENT

Property and equipment as of December 31, 2016 and 2015 consisted of the following (in millions):



	2016		2015
Drilling rigs and equipment	$	11,067.4	$	11,001.8
Other	180.8		180.0
Work in progress	1,744.3		1,537.6
	$	12,992.5	$	12,719.4

Work in progress as of December 31, 2016 primarily consisted of $1.1 billion related to the construction of ultra-deepwater drillships ENSCO DS-9 and ENSCO DS-10, $415.4 million related to the construction of ENSCO 140 and ENSCO 141 premium jackup rigs and $85.2 million related to the construction of ENSCO 123, an ultra-premium harsh environment jackup rig. ENSCO DS-9, ENSCO 140 and ENSCO 141 have been delivered by their respective shipyards but not yet placed into service as of December 31, 2016.

Work in progress as of December 31, 2015 primarily consisted of $1.1 billion related to the construction of ultra-deepwater drillships ENSCO DS-9 and ENSCO DS-10, $259.8 million related to the construction of ENSCO 140 and ENSCO 141 premium jackup rigs and $71.1 million related to the construction of ENSCO 123, an ultra-premium harsh environment jackup rig.

Impairment of Long-Lived Assets

During 2015, we recorded a pre-tax, non-cash loss on impairment of long-lived assets of $2,618.9 million, of which $2,470.3 million was included in (loss) income from continuing operations and $148.6 million was included in loss from discontinued operations, net, in our consolidated statement of operations. During 2014, we recorded a pre-tax, non-cash loss on impairment of long-lived assets of $2,463.1 million, of which $1,220.8 million was included in (loss) income from continuing operations and $1,242.3 million was included in loss from discontinued operations, net, in our consolidated statement of operations.

On a quarterly basis, we evaluate the carrying value of our property and equipment to identify events or changes in circumstances ("triggering events") that indicate the carrying value may not be recoverable. Beginning in 2014, Brent crude oil prices declined significantly from over $100 per barrel to $55 per barrel at December 31, 2014 and $35 per barrel at December 31, 2015. These prices resulted in significant capital spending reductions by our customers. Customers began delaying drilling programs and exploring subletting opportunities for contracted rigs thereby exacerbating supply pressure. In addition, certain customers requested contract concessions or terminated drilling contracts altogether. The significant supply and demand imbalance was anticipated to be adversely impacted by future newbuild deliveries, program delays and lower capital spending by operators. These adverse changes resulted in the deterioration of our forecasted day rates and utilization during the respective prior year periods. As a result, we concluded that triggering events had occurred during both 2014 and 2015.

For rigs whose carrying values were determined not to be recoverable, we recorded an impairment for the difference between their fair values and carrying values. We estimated the fair values of these rigs by applying either an income approach, using projected discounted cash flows, or a market approach. These valuations were based on unobservable inputs that require significant judgments for which there is limited information, including assumptions regarding future day rates, utilization, operating costs and capital requirements.

In instances where we applied an income approach, forecasted day rates and utilization took into account market conditions and our anticipated business outlook, both of which were impacted by the adverse changes in the business environment. The forecasted market day rates were depressed in the near term but were forecasted to grow in the longer-term and terminal period. Operating costs were forecasted using a combination of our historical average operating costs and expected future costs, adjusted for an estimated inflation factor. Capital requirements were based on our estimates of future capital costs, taking into consideration our historical trends. The estimated capital requirements included cash outflows to maintain the current operating condition of our rigs through their remaining useful lives.

In instances where we applied a market approach, the fair value was based on unobservable third-party estimated prices that would be received in exchange for the assets in an orderly transaction between market participants. We validated all third-party estimated prices using our forecasts of economic returns for the respective rigs or other market data.

If the global economy, our overall business outlook and/or our expectations regarding the marketability of one or more of our drilling rigs deteriorate further, we may conclude that a triggering event has occurred and perform a recoverability test that could lead to a material impairment charge in future periods.