Consolidated Statements of Changes in Equity and Income - USD ($) $ in Thousands	Total	Select	Common Stock	Common Stock Select	Capital in Excess of Par	Capital in Excess of Par Select	Retained Earnings	Retained Earnings Select	Total Stockholders’ Equity	Total Stockholders’ Equity Select	Non-controlling Interests	Non-controlling Interests Select
Balance at Dec. 31, 2014	$ 10,985	$ 10,985
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (loss) attributable to non-controlling interests	(2,190)	(2,190)
Issuance of non-controlling interests	218,005	218,005
Acquired non-controlling interests	14,196	14,196
Purchase of non-controlling interests	(876)	(876)
Distributions to non-controlling interests	(2,909)	(2,909)
Redemption adjustment on non-controlling interests	1,010	1,010
Balance at Dec. 31, 2015	238,221	238,221
Balance (in shares) at Dec. 31, 2014			131,233,000	0
Balance at Dec. 31, 2014	775,240	775,240	$ 131	$ 0	$ 413,706	$ 885,407	$ 325,678	$ (145,892)	$ 739,515	$ 739,515	$ 35,725	$ 35,725
Increase (Decrease) in Stockholders' Equity
Net income	130,736	130,736					130,736	130,736	130,736	130,736
Net income (loss) attributable to non-controlling interests	7,450	7,450									7,450	7,450
Dividends paid to common stockholders	$ (13,129)						(13,129)		(13,129)
Additional investment by Holdings		1,649				1,649				1,649
Dividends declared and paid to Holdings		(28,956)						(28,956)		(28,956)
Contribution related to restricted stock awards and stock option issuances by Holdings		13,969				13,969				13,969
Issuance and vesting of restricted stock (in shares)	1,385,000		1,385,000
Issuance and vesting of restricted stock	$ 13,916		$ 0		13,916				13,916
Tax benefit from stock based awards	$ 1,846	1,846			1,846	1,846			1,846	1,846
Repurchase of common shares (in shares)	(1,032,334)		(1,518,000)
Repurchase of common shares	$ (15,827)		$ 0		(8,168)		(7,659)		(15,827)
Stock option expense	$ 53				53				53
Exercise of stock options (in shares)	183,000		183,000
Exercise of stock options	$ 1,649		$ 0		1,649				1,649
Issuance of non-controlling interests	14,569	14,569			1,689	1,689			1,689	1,689	12,880	12,880
Acquired non-controlling interests	2,888	2,888									2,888	2,888
Purchase of non-controlling interests	(219)	(219)			(194)	(194)			(194)	(194)	(25)	(25)
Distributions to non-controlling interests	(9,732)	(9,732)									(9,732)	(9,732)
Redemption adjustment on non-controlling interests	(1,010)	(1,010)					(1,010)	(1,010)	(1,010)	(1,010)
Other	87	87			9	9			9	9	78	78
Balance (in shares) at Dec. 31, 2015			131,283,000	0
Balance at Dec. 31, 2015	908,517	908,517	$ 131	$ 0	424,506	904,375	434,616	(45,122)	859,253	859,253	49,264	49,264
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (loss) attributable to non-controlling interests	12,479	12,479
Purchase of non-controlling interests	(2,753)	(2,753)
Distributions to non-controlling interests	(3,231)	(3,231)
Redemption adjustment on non-controlling interests	177,216	177,216
Other	227	227
Balance at Dec. 31, 2016	422,159	422,159
Increase (Decrease) in Stockholders' Equity
Net income	115,411	115,411					115,411	115,411	115,411	115,411
Net income (loss) attributable to non-controlling interests	$ (2,620)	(2,620)									(2,620)	(2,620)
Additional investment by Holdings		1,672				1,672				1,672
Dividends declared and paid to Holdings		(2,929)						(2,929)		(2,929)
Contribution related to restricted stock awards and stock option issuances by Holdings		16,644				16,644				16,644
Issuance and vesting of restricted stock (in shares)	1,426,000		1,344,000
Issuance and vesting of restricted stock	$ 16,640		$ 1		16,639				16,640
Repurchase of common shares (in shares)	0		(232,000)
Repurchase of common shares	$ (2,929)		$ 0		(1,333)		(1,596)		(2,929)
Stock option expense	$ 4				4				4
Exercise of stock options (in shares)	202,000		202,000
Exercise of stock options	$ 1,672		$ 0		1,672				1,672
Issuance of non-controlling interests	50,178	50,178			2,377	2,377			2,377	2,377	47,801	47,801
Acquired non-controlling interests	2,514	2,514									2,514	2,514
Purchase of non-controlling interests	654	654			75	75	579	579	654	654
Distributions to non-controlling interests	(7,324)	(7,324)									(7,324)	(7,324)
Redemption adjustment on non-controlling interests	(177,216)	(177,216)					(177,216)	(177,216)	(177,216)	(177,216)
Other	$ 400	$ 400			(32)	(32)	(109)	(109)	(141)	(141)	541	541
Balance (in shares) at Dec. 31, 2016	132,596,758	100	132,597,000	0
Balance at Dec. 31, 2016	$ 905,901	$ 905,901	$ 132	$ 0	443,908	925,111	371,685	(109,386)	815,725	815,725	90,176	90,176
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (loss) attributable to non-controlling interests	35,639	35,639
Purchase of non-controlling interests	(127)	(127)
Distributions to non-controlling interests	(5,207)	(5,207)
Redemption adjustment on non-controlling interests	187,506	187,506
Other	848	848
Balance at Dec. 31, 2017	640,818	640,818
Increase (Decrease) in Stockholders' Equity
Net income	177,184	177,184					177,184	177,184	177,184	177,184
Net income (loss) attributable to non-controlling interests	$ 7,822	7,822									7,822	7,822
Additional investment by Holdings		2,017				2,017				2,017
Dividends declared and paid to Holdings		(4,753)						(4,753)		(4,753)
Contribution related to restricted stock awards and stock option issuances by Holdings		18,291				18,291				18,291
Issuance and vesting of restricted stock (in shares)	1,598,000		1,571,000
Issuance and vesting of restricted stock	$ 18,291		$ 2		18,289				18,291
Repurchase of common shares (in shares)	0		(280,000)
Repurchase of common shares	$ (4,753)		$ 0		(2,666)		(2,087)		(4,753)
Exercise of stock options (in shares)	226,845		227,000
Exercise of stock options	$ 2,017		$ 0		2,017				2,017
Issuance of non-controlling interests	18,280	18,280			1,951	1,951			1,951	1,951	16,329	16,329
Purchase of non-controlling interests	7	7					7	7	7	7
Distributions to non-controlling interests	(5,293)	(5,293)									(5,293)	(5,293)
Redemption adjustment on non-controlling interests	(187,506)	(187,506)					(187,506)	(187,506)	(187,506)	(187,506)
Other	$ 654	$ 654					452	452	452	452	202	202
Balance (in shares) at Dec. 31, 2017	134,114,715	100	134,115,000	0
Balance at Dec. 31, 2017	$ 932,604	$ 932,604	$ 134	$ 0	$ 463,499	$ 947,370	$ 359,735	$ (124,002)	$ 823,368	$ 823,368	$ 109,236	$ 109,236