Condensed Consolidating Financial Information - Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Consolidating Statements Of Cash Flows
Net cash provided by (used for) operating activities		$ 531,905	$ 856,556	$ 1,781,911
Cash flows from investing activities:
Purchases of investments		(24)	(9)	(319)
Sales and maturities of investments		739	961	23,992
Proceeds from sales of unconsolidated affiliate				750
Cash paid for acquisition of businesses, net of cash acquired		(22,278)	(80,187)	(72,534)
Investment in unconsolidated affiliates			(445)	(2,365)
Capital expenditures		(395,455)	(867,106)	(1,821,315)
Proceeds from sales of assets and insurance claims		34,831	68,206	156,761
Other		64	1,081	(1,879)
Proceeds from merger transaction			650,050
Net cash (used for) provided by investing activities		(382,123)	(227,449)	(1,716,909)
Cash flows from financing activities:
Increase (decrease) in cash overdrafts		3	645	(6,151)
Proceeds from issuance of long-term debt		600,000
Debt issuance costs		(11,520)	(1,847)
Proceeds from revolving credit facilities		611,500		465,000
Reduction in revolving credit facilities		(611,500)	(450,000)	(230,932)
Proceeds from (payments for) issuance of common shares		967	1,296	30,263
Repurchase of common shares		(1,687)	(99,598)	(250,037)
Reduction of long-term debt		(493,612)	(27,478)	(46,800)
Dividends to shareholders	$ (17,100)	(50,924)	(69,363)	(59,145)
Proceeds from (payments for) commercial paper, net		(8,000)	(525,119)	203,275
Proceeds from term Loan			625,000
Payments on term loan		(162,500)	(300,000)
Proceeds from (payments for) short-term borrowings		(6,211)	318
Proceeds from parent contributions				30,263
Other		(4,732)	(7,767)	(11,550)
Redemption of subsidiary Preferred Shares				(70,875)
Cash proceeds from noncontrolling Interest			3,972
Net cash (used for) provided by financing activities		(138,216)	(849,941)	69,848
Effect of exchange rate changes on cash and cash equivalents		(2,003)	(25,785)	(23,616)
Net increase (decrease) in cash and cash equivalents		9,563	(246,619)	111,234
Cash and cash equivalents, beginning of period		254,530	501,149	389,915
Cash and cash equivalents, end of period	264,093	264,093	254,530	501,149
Reportable Legal Entities | Parent Company
Condensed Consolidating Statements Of Cash Flows
Net cash provided by (used for) operating activities		58,406	39,478	26,943
Cash flows from investing activities:
Proceeds from merger transaction			5,500
Net cash (used for) provided by investing activities			5,500
Cash flows from financing activities:
Proceeds from (payments for) issuance of common shares		967	1,296	16,424
Dividends to shareholders		(59,866)	(79,304)	(65,450)
Proceeds from parent contributions				30,263
Proceeds from issuance of intercompany debt		45,500
Paydown of intercompany debt		(40,000)	(27,000)	(55,000)
Other		(4,732)	(7,767)	(7,740)
Proceeds (issuance) of intercompany debt			67,500	55,000
Net cash (used for) provided by financing activities		(58,131)	(45,275)	(26,503)
Net increase (decrease) in cash and cash equivalents		275	(297)	440
Cash and cash equivalents, beginning of period		873	1,170	730
Cash and cash equivalents, end of period	1,148	1,148	873	1,170
Reportable Legal Entities | Guarantor Subsidiaries
Condensed Consolidating Statements Of Cash Flows
Net cash provided by (used for) operating activities		(233,738)	(217,685)	(71,982)
Cash flows from investing activities:
Investment in unconsolidated affiliates		(86,459)
Change in intercompany balances		103,384	135,518	(418,315)
Proceeds from merger transaction			646,078
Net cash (used for) provided by investing activities		16,925	781,596	(418,315)
Cash flows from financing activities:
Proceeds from issuance of long-term debt		600,000
Debt issuance costs		(11,520)	(1,847)
Proceeds from revolving credit facilities		610,000		450,000
Reduction in revolving credit facilities		(610,000)	(450,000)	(170,000)
Reduction of long-term debt		(350,000)
Proceeds from (payments for) commercial paper, net		(8,000)	(525,119)	203,275
Proceeds from term Loan			625,000
Payments on term loan		(162,500)	(300,000)
Proceeds from parent contributions		(159,000)
Proceeds (issuance) of intercompany debt			88,058
Net cash (used for) provided by financing activities		226,980	(563,908)	483,275
Net increase (decrease) in cash and cash equivalents		10,167	3	(7,022)
Cash and cash equivalents, beginning of period		10	7	7,029
Cash and cash equivalents, end of period	10,177	10,177	10	7
Reportable Legal Entities | Other Subsidiaries (Non-Guarantors)
Condensed Consolidating Statements Of Cash Flows
Net cash provided by (used for) operating activities		757,660	1,066,026	1,816,831
Cash flows from investing activities:
Purchases of investments		(24)	(9)	(319)
Sales and maturities of investments		739	961	23,992
Proceeds from sales of unconsolidated affiliate				750
Cash paid for acquisition of businesses, net of cash acquired		(22,278)	(80,187)	(72,534)
Investment in unconsolidated affiliates		(159,000)	(445)	(2,365)
Capital expenditures		(395,455)	(867,106)	(1,821,315)
Proceeds from sales of assets and insurance claims		34,831	68,206	156,761
Change in intercompany balances		(103,384)	(135,518)	418,315
Other		64	1,081	(1,879)
Proceeds from merger transaction			(1,528)
Net cash (used for) provided by investing activities		(644,507)	(1,014,545)	(1,298,594)
Cash flows from financing activities:
Increase (decrease) in cash overdrafts		3	645	(6,151)
Proceeds from revolving credit facilities		1,500		15,000
Reduction in revolving credit facilities		(1,500)		(60,932)
Repurchase of common shares		(1,687)	(99,598)	(250,037)
Reduction of long-term debt		(143,612)	(27,478)
Proceeds from (payments for) short-term borrowings		(6,211)	318
Proceeds from parent contributions		(86,458)
Proceeds from issuance of intercompany debt		(45,500)
Paydown of intercompany debt		40,000	27,000	55,000
Payments on parent (Equity or N/P)		(41,480)	(21,322)
Other				(3,810)
Proceeds (issuance) of intercompany debt			(155,558)	(55,000)
Redemption of subsidiary Preferred Shares				(70,875)
Cash proceeds from noncontrolling Interest			3,972
Net cash (used for) provided by financing activities		(112,029)	(272,021)	(376,805)
Effect of exchange rate changes on cash and cash equivalents		(2,003)	(25,785)	(23,616)
Net increase (decrease) in cash and cash equivalents		(879)	(246,325)	117,816
Cash and cash equivalents, beginning of period		253,647	499,972	382,156
Cash and cash equivalents, end of period	$ 252,768	252,768	253,647	499,972
Consolidating Adjustments
Condensed Consolidating Statements Of Cash Flows
Net cash provided by (used for) operating activities		(50,423)	(31,263)	10,119
Cash flows from investing activities:
Investment in unconsolidated affiliates		245,459
Net cash (used for) provided by investing activities		245,459
Cash flows from financing activities:
Proceeds from (payments for) issuance of common shares				(16,424)
Dividends to shareholders		8,942	9,941	6,305
Proceeds from parent contributions		245,458
Payments on parent (Equity or N/P)		41,480	21,322
Net cash (used for) provided by financing activities		$ (195,036)	$ 31,263	$ (10,119)