Held for Sale and Discontinued Operations Schedule of Financial Results of DMG's Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net income from discontinued operations, net of tax	$ 79,392	$ 69,696	$ 109,697	$ 63,910
DMG held for sale | Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	1,330,777	1,252,430	2,713,059	2,480,362
Expenses	1,201,633	1,192,528	2,539,787	2,418,935
Income from operations of discontinued operations before taxes	129,144	59,902	173,272	61,427
Income tax expense (benefit)	26,730	(9,794)	40,553	(2,483)
Loss on sale of discontinued operations before taxes	$ (23,022)	$ 0	$ (23,022)	$ 0