Segment Information (Financial Information) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Operating revenue	$ 467,642	$ 436,727	$ 385,086	$ 352,920	$ 352,841	$ 375,571	$ 374,738	$ 337,723	$ 1,642,375	$ 1,440,873	$ 1,436,370
Depreciation and amortization									174,445	175,100	181,142
Operating Income/(Loss)	120,395	73,183	82,211	55,193	50,365	61,867	1,801	8,002	330,982	122,035	157,370
Equity in earnings of affiliates, net of tax	0	$ 971	$ 376	$ 512	58	$ 607	$ 313	$ (422)	1,859	556	1,493
Net income/(loss) from continuing operations									264,250	33,770	74,010
Capital expenditures									99,110	114,746	84,152
Statement of Financial Position [Abstract]
Investments in affiliates, net	0				16,666				0	16,666
Long-Lived Assets	3,527,359				3,552,345				3,527,359	3,552,345
Total assets	4,080,777				3,957,295				4,080,777	3,957,295
Domestic
Income Statement [Abstract]
Operating revenue									1,454,592	1,256,178	1,267,514
Statement of Financial Position [Abstract]
Total assets	3,112,808				3,069,427				3,112,808	3,069,427
Foreign
Income Statement [Abstract]
Operating revenue									187,783	184,695	168,856
Statement of Financial Position [Abstract]
Total assets	414,551				482,918				414,551	482,918
Operating Segments | PIRM
Income Statement [Abstract]
Operating revenue									681,912	663,016	646,804
Depreciation and amortization									93,640	94,862	95,866
Operating Income/(Loss)									90,931	53,607	59,395
Equity in earnings of affiliates, net of tax									2,483	930	2,093
Net income/(loss) from continuing operations									129,865	47,759	75,336
Capital expenditures									61,934	56,065	48,019
Statement of Financial Position [Abstract]
Investments in affiliates, net	0				14,179				0	14,179
Long-Lived Assets	1,669,280				1,756,984				1,669,280	1,756,984
Total assets	1,892,424				1,932,643				1,892,424	1,932,643
Operating Segments | PIRM | Domestic
Income Statement [Abstract]
Operating revenue									494,129	478,321	477,948
Statement of Financial Position [Abstract]
Long-Lived Assets	1,254,729				1,274,066				1,254,729	1,274,066
Operating Segments | PIRM | Foreign
Income Statement [Abstract]
Operating revenue									187,783	184,695	168,856
Statement of Financial Position [Abstract]
Long-Lived Assets	414,551				482,918				414,551	482,918
Operating Segments | UWS
Income Statement [Abstract]
Operating revenue									972,831	787,368	796,550
Depreciation and amortization									48,126	51,337	62,011
Operating Income/(Loss)									431,690	194,654	201,350
Equity in earnings of affiliates, net of tax									0	(12)	(23)
Net income/(loss) from continuing operations									431,873	194,454	201,259
Capital expenditures									8,481	9,306	9,264
Statement of Financial Position [Abstract]
Investments in affiliates, net	0				0				0	0
Long-Lived Assets	1,835,368				1,874,624				1,835,368	1,874,624
Total assets	2,013,089				2,008,233				2,013,089	2,008,233
Operating Segments | UWS | Domestic
Income Statement [Abstract]
Operating revenue									972,831	787,368	796,536
Statement of Financial Position [Abstract]
Long-Lived Assets	1,835,368				1,874,624				1,835,368	1,874,624
Operating Segments | UWS | Foreign
Income Statement [Abstract]
Operating revenue									0	0	0
Statement of Financial Position [Abstract]
Long-Lived Assets	0				0				0	0
Corporate
Income Statement [Abstract]
Operating revenue									0	0	0
Depreciation and amortization									32,679	28,901	23,265
Operating Income/(Loss)									(191,639)	(126,226)	(103,375)
Equity in earnings of affiliates, net of tax									(624)	(362)	(577)
Net income/(loss) from continuing operations									(297,488)	(208,443)	(202,585)
Capital expenditures									28,695	49,375	26,869
Statement of Financial Position [Abstract]
Investments in affiliates, net	0				2,487				0	2,487
Long-Lived Assets	5,891,296				5,851,913				5,891,296	5,851,913
Total assets	6,046,238				5,950,472				6,046,238	5,950,472
Corporate | Domestic
Income Statement [Abstract]
Operating revenue									0	0	0
Statement of Financial Position [Abstract]
Long-Lived Assets	5,131,183				5,093,349				5,131,183	5,093,349
Corporate | Foreign
Income Statement [Abstract]
Operating revenue									0	0	0
Statement of Financial Position [Abstract]
Long-Lived Assets	760,113				758,564				760,113	758,564
Eliminations
Income Statement [Abstract]
Operating revenue									(12,368)	(9,511)	(6,984)
Depreciation and amortization									0	0	0
Operating Income/(Loss)									0	0	0
Equity in earnings of affiliates, net of tax									0	0	0
Net income/(loss) from continuing operations									0	0	0
Capital expenditures									0	0	0
Statement of Financial Position [Abstract]
Investments in affiliates, net	0				0				0	0
Long-Lived Assets	(5,868,585)				(5,931,176)				(5,868,585)	(5,931,176)
Total assets	(5,870,974)				(5,934,053)				(5,870,974)	(5,934,053)
Eliminations | Domestic
Income Statement [Abstract]
Operating revenue									(12,368)	(9,511)	(6,970)
Statement of Financial Position [Abstract]
Long-Lived Assets	(5,108,472)				(5,172,612)				(5,108,472)	(5,172,612)
Eliminations | Foreign
Income Statement [Abstract]
Operating revenue									0	0	$ 0
Statement of Financial Position [Abstract]
Long-Lived Assets	$ (760,113)				$ (758,564)				$ (760,113)	$ (758,564)