Employee Benefit Plans	12 Months Ended
Dec. 31, 2017
Employee Benefit Plans [Abstract]
Employee Benefit Plans Disclosure	11. EMPLOYEE BENEFIT PLANS The Company maintains various benefit plans, including defined contribution plans, defined benefit plans and deferred compensation plans, for which certain of the Company’s subsidiaries are the plan sponsors. The CHS/Community Health Systems, Inc. Retirement Savings Plan is a defined contribution plan which covers the majority of the employees at subsidiaries owned prior to the HMA merger. Employees at these locations whose employment is covered by collective bargaining agreements are generally eligible to participate in the CHS/Community Health Systems, Inc. Standard 401(k) Plan. The Company also maintains the Health Management Associates, Inc. Retirement Savings Plan, a defined contribution plan covering substantially all of the employees formerly employed by HMA. Total expense to the Company under the 401(k) plans was $94 million, $98 million and $103 million for the years ended December 31, 2017, 2016 and 2015, respectively, and is recorded in salaries and benefits expense on the consolidated statements of (loss) income. The Company maintains unfunded deferred compensation plans that allow participants to defer receipt of a portion of their compensation. The liability for the deferred compensation plans was $189 million and $229 million as of December 31, 2017 and 2016, respectively, and is included in other long-term liabilities on the consolidated balance sheets. The Company had assets of $173 million and $219 million as of December 31, 2017 and 2016, respectively, in a non-qualified plan trust generally designated to pay benefits of the deferred compensation plans, consisting of trading securities of $37 million and $80 million as of December 31, 2017 and 2016, respectively, and company-owned life insurance contracts of $136 million and $139 million as of December 31, 2017 and 2016, respectively. The Company provides an unfunded Supplemental Executive Retirement Plan (“SERP”) for certain members of its executive management. The Company uses a December 31 measurement date for the benefit obligations and a January 1 measurement date for its net periodic costs for the SERP. Variances from actuarially assumed rates will result in increases or decreases in benefit obligations and net periodic cost in future periods. Benefits expense under the SERP was $16 million, $12 million and $12 million for the years ended December 31, 2017, 2016 and 2015, respectively. The accrued benefit liability for the SERP totaled $83 million and $122 million at December 31, 2017 and 2016, respectively, and is included in other long-term liabilities on the consolidated balance sheets. The weighted-average assumptions used in determining net periodic cost for the year ended December 31, 2017 was a discount rate of 3.6% and annual salary increase of 2.0%. The Company had available-for-sale securities in a rabbi trust generally designated to pay benefits of the SERP in the amounts of $99 million and $131 million at December 31, 2017 and 2016, respectively. These amounts are included in other assets, net on the consolidated balance sheets. During the year ended December 31, 2017, certain members of executive management of the Company that were participants in the SERP retired and met the requirements for payout of their SERP retirement benefit. The SERP payout provisions require payment to the participant in an actuarially determined lump sum amount six months after the participant retires from the Company. Such amounts have been or will be paid out of the rabbi trust during the latter half of 2017 and first half of 2018. As required by the pension accounting rules in U.S. GAAP, the Company recognized a non-cash settlement loss of approximately $6 million during the year ended December 31, 2017, and will recognize a non-cash settlement of approximately $1 million during the year ended December 31, 2018, which represent a pro-rata portion of the accumulated unrecognized actuarial loss out of accumulated other comprehensive loss. The Company maintains the CHS/Community Health Systems, Inc. Retirement Income Plan (“Pension Plan”), which is a defined benefit, non-contributory pension plan that covers certain employees at three of its formerly owned hospitals. The Pension Plan provides benefits to covered individuals satisfying certain age and service requirements. Employer contributions to the Pension Plan are in accordance with the minimum funding requirements of the Employee Retirement Income Security Act of 1974, as amended. The Company expects to make no contribution to the Pension Plan in 2018. The Company uses a December 31 measurement date for the benefit obligations and a January 1 measurement date for its net periodic costs for the Pension Plan. Variances from actuarially assumed rates will result in increases or decreases in benefit obligations, net periodic cost and funding requirements in future periods. Benefits expense under the Pension Plan was $7 million for the year ended December 31, 2017, and was less than $1 million for both the years ended December 31, 2016 and 2015. The accrued benefit liability for the Pension Plan totaled $12 million and $16 million at December 31, 2017 and 2016, respectively, and is included in other long-term liabilities on the consolidated balance sheets. The weighted-average assumptions used for determining the net periodic cost for the year ended December 31, 2017 was a discount rate of 4.1% and the expected long-term rate of return on assets of 7.0%.

11. EMPLOYEE BENEFIT PLANS

The Company maintains various benefit plans, including defined contribution plans, defined benefit plans and deferred compensation plans, for which certain of the Company’s subsidiaries are the plan sponsors. The CHS/Community Health Systems, Inc. Retirement Savings Plan is a defined contribution plan which covers the majority of the employees at subsidiaries owned prior to the HMA merger. Employees at these locations whose employment is covered by collective bargaining agreements are generally eligible to participate in the CHS/Community Health Systems, Inc. Standard 401(k) Plan. The Company also maintains the Health Management Associates, Inc. Retirement Savings Plan, a defined contribution plan covering substantially all of the employees formerly employed by HMA. Total expense to the Company under the 401(k) plans was $94 million, $98 million and $103 million for the years ended December 31, 2017, 2016 and 2015, respectively, and is recorded in salaries and benefits expense on the consolidated statements of (loss) income.

The Company maintains unfunded deferred compensation plans that allow participants to defer receipt of a portion of their compensation. The liability for the deferred compensation plans was $189 million and $229 million as of December 31, 2017 and 2016, respectively, and is included in other long-term liabilities on the consolidated balance sheets. The Company had assets of $173 million and $219 million as of December 31, 2017 and 2016, respectively, in a non-qualified plan trust generally designated to pay benefits of the deferred compensation plans, consisting of trading securities of $37 million and $80 million as of December 31, 2017 and 2016, respectively, and company-owned life insurance contracts of $136 million and $139 million as of December 31, 2017 and 2016, respectively.

The Company provides an unfunded Supplemental Executive Retirement Plan (“SERP”) for certain members of its executive management. The Company uses a December 31 measurement date for the benefit obligations and a January 1 measurement date for its net periodic costs for the SERP. Variances from actuarially assumed rates will result in increases or decreases in benefit obligations and net periodic cost in future periods. Benefits expense under the SERP was $16 million, $12 million and $12 million for the years ended December 31, 2017, 2016 and 2015, respectively. The accrued benefit liability for the SERP totaled $83 million and $122 million at December 31, 2017 and 2016, respectively, and is included in other long-term liabilities on the consolidated balance sheets. The weighted-average assumptions used in determining net periodic cost for the year ended December 31, 2017 was a discount rate of 3.6% and annual salary increase of 2.0%. The Company had available-for-sale securities in a rabbi trust generally designated to pay benefits of the SERP in the amounts of $99 million and $131 million at December 31, 2017 and 2016, respectively. These amounts are included in other assets, net on the consolidated balance sheets.

During the year ended December 31, 2017, certain members of executive management of the Company that were participants in the SERP retired and met the requirements for payout of their SERP retirement benefit. The SERP payout provisions require payment to the participant in an actuarially determined lump sum amount six months after the participant retires from the Company. Such amounts have been or will be paid out of the rabbi trust during the latter half of 2017 and first half of 2018. As required by the pension accounting rules in U.S. GAAP, the Company recognized a non-cash settlement loss of approximately $6 million during the year ended December 31, 2017, and will recognize a non-cash settlement of approximately $1 million during the year ended December 31, 2018, which represent a pro-rata portion of the accumulated unrecognized actuarial loss out of accumulated other comprehensive loss.

The Company maintains the CHS/Community Health Systems, Inc. Retirement Income Plan (“Pension Plan”), which is a defined benefit, non-contributory pension plan that covers certain employees at three of its formerly owned hospitals. The Pension Plan provides benefits to covered individuals satisfying certain age and service requirements. Employer contributions to the Pension Plan are in accordance with the minimum funding requirements of the Employee Retirement Income Security Act of 1974, as amended. The Company expects to make no contribution to the Pension Plan in 2018. The Company uses a December 31 measurement date for the benefit obligations and a January 1 measurement date for its net periodic costs for the Pension Plan. Variances from actuarially assumed rates will result in increases or decreases in benefit obligations, net periodic cost and funding requirements in future periods. Benefits expense under the Pension Plan was $7 million for the year ended December 31, 2017, and was less than $1 million for both the years ended December 31, 2016 and 2015. The accrued benefit liability for the Pension Plan totaled $12 million and $16 million at December 31, 2017 and 2016, respectively, and is included in other long-term liabilities on the consolidated balance sheets. The weighted-average assumptions used for determining the net periodic cost for the year ended December 31, 2017 was a discount rate of 4.1% and the expected long-term rate of return on assets of 7.0%.