Supplemental Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Operations And Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Net patient service revenue	$ 263,380	$ 245,950	$ 520,137	$ 459,858
Management fees	15,211	16,856	31,081	33,453
Other revenue	6,430	3,189	12,262	6,119
(Loss) income from equity investment	188	(97)	212	(135)
Total revenues	285,209	265,898	563,692	499,295
Expenses:
Salaries and benefits	147,397	135,803	294,356	261,712
Medical supplies	24,774	24,502	51,065	46,236
Facility rent expenses	16,922	17,167	33,797	32,662
Other operating expenses	16,073	16,096	30,997	30,477
General and administrative expenses	43,776	34,060	72,686	64,174
Depreciation and amortization	22,242	22,162	44,811	42,884
Provision for doubtful accounts	3,753	3,428	8,221	7,724
Interest expense, net	24,326	29,899	50,013	57,426
Impairment loss		182,000		182,000
Early extinguishment of debt	37,390		37,390
Equity initial public offering expenses		4,163		4,163
Loss on sale leaseback transaction				135
Fair value adjustment of noncontrolling interest and earn-out liability	2,745	204	3,205	403
Fair value adjustment of embedded derivative	5,217		6,559
Loss on foreign currency transactions	(31)	79	211	107
Gain on foreign currency derivative contracts				(4)
Total expenses	344,584	469,563	633,311	730,099
Loss before income taxes	(59,375)	(203,665)	(69,619)	(230,804)
Income tax (benefit) expense	3,088	934	5,778	3,040
Net loss	(62,463)	(204,599)	(75,397)	(233,844)	$ (349,300)	$ (78,200)	$ (151,100)
Net income attributable to noncontrolling interests - redeemable and non-redeemable	(2,075)	(2,925)	(4,383)	(3,861)
Net loss attributable to 21st Century Oncology Holdings, Inc. shareholder	(64,538)	(207,524)	(79,780)	(237,705)
Other comprehensive loss
Unrealized comprehensive (loss) income:	(2,062)	(750)	(4,497)	(10,606)
Comprehensive loss	(64,525)	(205,349)	(79,894)	(244,450)
Comprehensive income attributable to noncontrolling interests-redeemable and non-redeemable:	(1,866)	(2,873)	(3,931)	(2,990)
Comprehensive loss attributable to 21st Century Oncology Holdings, Inc. shareholder	(66,391)	(208,222)	(83,825)	(247,440)
Parent [Member]
Revenues:
(Loss) income from equity investment	(58,748)	(204,012)	(75,506)	(243,196)
Intercompany revenue	658		1,326
Total revenues	(58,090)	(204,012)	(74,180)	(243,196)
Expenses:
Salaries and benefits	2	35	4	69
General and administrative expenses		12		12
Interest expense, net	(1)		(1)
Equity initial public offering expenses		4,163		4,163
Fair value adjustment of noncontrolling interest and earn-out liability	3,083		3,083
Fair value adjustment of embedded derivative	5,217		6,559
Total expenses	8,301	4,210	9,645	4,244
Loss before income taxes	(66,391)	(208,222)	(83,825)	(247,440)
Net loss	(66,391)	(208,222)	(83,825)	(247,440)
Net loss attributable to 21st Century Oncology Holdings, Inc. shareholder	(66,391)	(208,222)	(83,825)	(247,440)
Other comprehensive loss
Comprehensive loss	(66,391)	(208,222)	(83,825)	(247,440)
Comprehensive loss attributable to 21st Century Oncology Holdings, Inc. shareholder	(66,391)	(208,222)	(83,825)	(247,440)
21C [Member]
Revenues:
Other revenue	50	20	82	41
(Loss) income from equity investment	(5,271)	(181,789)	(1,554)	(199,226)
Intercompany revenue	367	238	706	445
Total revenues	(4,854)	(181,531)	(766)	(198,740)
Expenses:
General and administrative expenses	549	233	1,091	364
Interest expense, net	21,496	22,295	42,573	44,214
Early extinguishment of debt	31,076		31,076
Gain on foreign currency derivative contracts				(4)
Total expenses	53,121	22,528	74,740	44,574
Loss before income taxes	(57,975)	(204,059)	(75,506)	(243,314)
Income tax (benefit) expense		430		380
Net loss	(57,975)	(204,489)	(75,506)	(243,694)
Net loss attributable to 21st Century Oncology Holdings, Inc. shareholder	(57,975)	(204,489)	(75,506)	(243,694)
Other comprehensive loss
Comprehensive loss	(57,975)	(204,489)	(75,506)	(243,694)
Comprehensive loss attributable to 21st Century Oncology Holdings, Inc. shareholder	(57,975)	(204,489)	(75,506)	(243,694)
Subsidiary Guarantors [Member]
Revenues:
Net patient service revenue	140,358	133,854	278,822	264,592
Management fees	14,652	16,526	30,142	32,845
Other revenue	5,514	2,955	9,416	5,554
(Loss) income from equity investment	5,954	2,014	7,982	(6,102)
Intercompany revenue	21,053	23,088	40,022	42,293
Total revenues	187,531	178,437	366,384	339,182
Expenses:
Salaries and benefits	91,007	88,555	184,283	180,926
Medical supplies	16,547	17,427	34,067	32,964
Facility rent expenses	11,496	11,573	22,857	23,252
Other operating expenses	9,800	10,227	17,644	19,126
General and administrative expenses	35,373	27,636	57,012	52,820
Depreciation and amortization	17,142	17,739	34,776	35,078
Provision for doubtful accounts	2,036	2,566	4,362	5,357
Interest expense, net	2,325	4,216	6,371	8,051
Impairment loss		182,000		182,000
Early extinguishment of debt	6,314		6,314
Electronic health records incentive payment	(114)	7		75
Loss on sale leaseback transaction				135
Fair value adjustment of noncontrolling interest and earn-out liability	(110)	204	122	403
Total expenses	191,816	362,150	367,808	540,187
Loss before income taxes	(4,285)	(183,713)	(1,424)	(201,005)
Income tax (benefit) expense	15	(1,632)	(30)	(1,631)
Net loss	(4,300)	(182,081)	(1,394)	(199,374)
Net loss attributable to 21st Century Oncology Holdings, Inc. shareholder	(4,300)	(182,081)	(1,394)	(199,374)
Other comprehensive loss
Comprehensive loss	(4,300)	(182,081)	(1,394)	(199,374)
Comprehensive loss attributable to 21st Century Oncology Holdings, Inc. shareholder	(4,300)	(182,081)	(1,394)	(199,374)
Subsidiary Non-Guarantors [Member]
Revenues:
Net patient service revenue	123,022	112,096	241,315	195,266
Management fees	559	330	939	608
Other revenue	866	214	2,764	524
(Loss) income from equity investment	7		20	9
Total revenues	124,454	112,640	245,038	196,407
Expenses:
Salaries and benefits	56,388	47,213	110,069	80,717
Medical supplies	8,227	7,075	16,998	13,272
Facility rent expenses	5,426	5,594	10,940	9,410
Other operating expenses	6,273	5,869	13,353	11,351
General and administrative expenses	7,854	6,179	14,583	10,978
Depreciation and amortization	5,100	4,423	10,035	7,806
Provision for doubtful accounts	1,717	862	3,859	2,367
Interest expense, net	506	3,388	1,070	5,161
Electronic health records incentive payment	114	(7)		(75)
Fair value adjustment of noncontrolling interest and earn-out liability	(228)
Loss on foreign currency transactions	(31)	79	211	107
Intercompany expenses	22,078	23,326	42,054	42,738
Total expenses	113,424	104,001	223,172	183,832
Loss before income taxes	11,030	8,639	21,866	12,575
Income tax (benefit) expense	3,073	2,136	5,808	4,291
Net loss	7,957	6,503	16,058	8,284
Net income attributable to noncontrolling interests - redeemable and non-redeemable	952	(1,487)		(1,985)
Net loss attributable to 21st Century Oncology Holdings, Inc. shareholder	8,909	5,016	16,058	6,299
Other comprehensive loss
Unrealized comprehensive (loss) income:	(2,062)	(750)	(4,497)	(10,606)
Comprehensive loss	5,895	5,753	11,561	(2,322)
Comprehensive loss attributable to 21st Century Oncology Holdings, Inc. shareholder	5,895	5,753	11,561	(2,322)
Eliminations [Member]
Revenues:
(Loss) income from equity investment	58,246	383,690	69,270	448,380
Intercompany revenue	(22,078)	(23,326)	(42,054)	(42,738)
Total revenues	36,168	360,364	27,216	405,642
Expenses:
Intercompany expenses	(22,078)	(23,326)	(42,054)	(42,738)
Total expenses	(22,078)	(23,326)	(42,054)	(42,738)
Loss before income taxes	58,246	383,690	69,270	448,380
Net loss	58,246	383,690	69,270	448,380
Net income attributable to noncontrolling interests - redeemable and non-redeemable	(3,027)	(1,438)	(4,383)	(1,876)
Net loss attributable to 21st Century Oncology Holdings, Inc. shareholder	55,219	382,252	64,887	446,504
Other comprehensive loss
Comprehensive loss	58,246	383,690	69,270	448,380
Comprehensive income attributable to noncontrolling interests-redeemable and non-redeemable:	(1,866)	(2,873)	(3,931)	(2,990)
Comprehensive loss attributable to 21st Century Oncology Holdings, Inc. shareholder	$ 56,380	$ 380,817	$ 65,339	$ 445,390