Condensed Consolidating Financial Information - Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Condensed Consolidating Statements Of Cash Flows
Net cash provided by (used for) operating activities	$ 404,768	$ 605,011
Cash flows from investing activities:
Purchases of investments	(24)	(8)
Sales and maturities of investments	643	859
Investment in unconsolidated affiliates		(445)
Capital expenditures	(284,950)	(744,047)
Proceeds from sales of assets and insurance claims	26,597	30,164
Other	(19)	1,700
Cash paid for acquisition of businesses, net		(57,909)
Proceeds from merger transaction		650,050
Net cash (used for) provided by investing activities	(257,753)	(119,636)
Cash flows from financing activities:
Increase (decrease) in cash overdrafts	5	363
Proceeds from revolving credit facilities	560,000
Reduction in revolving credit facilities	(260,000)	(450,000)
Proceeds from (payments for) issuance of common shares	562	1,198
Repurchase of common shares	(1,687)	(44,978)
Reduction of long-term debt	(492,625)
Dividends to shareholders	(33,927)	(52,489)
Proceeds from (payments for) commercial paper, net	15,000	(162,544)
Proceeds from (payments for) short-term borrowings	(6,388)	2,792
Other	(4,313)	(7,534)
Proceeds from term Loan		300,000
Payments on term loan		(300,000)
Dividends to shareholders	33,927	52,489
Net cash (used for) provided by financing activities	(223,373)	(713,192)
Effect of exchange rate changes on cash and cash equivalents	(1,129)	(21,966)
Net increase (decrease) in cash and cash equivalents	(77,487)	(249,783)
Cash and cash equivalents, beginning of period	254,530	501,149
Cash and cash equivalents, end of period	177,043	251,366
Reportable Legal Entities | Parent Company
Condensed Consolidating Statements Of Cash Flows
Net cash provided by (used for) operating activities	18,320	39,956
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	562	1,198
Dividends to shareholders	(39,887)	(59,470)
Proceeds from issuance of intercompany debt	25,500	47,000
Other	(4,313)	(7,534)
Dividends to shareholders	39,887	59,470
Paydown of intercompany debt		(27,000)
Net cash (used for) provided by financing activities	(18,138)	(45,806)
Net increase (decrease) in cash and cash equivalents	182	(350)
Cash and cash equivalents, beginning of period	873	1,170
Cash and cash equivalents, end of period	1,055	820
Reportable Legal Entities | Guarantor Subsidiaries
Condensed Consolidating Statements Of Cash Flows
Net cash provided by (used for) operating activities	(276,655)	(188,781)
Cash flows from investing activities:
Investment in unconsolidated affiliates	(86,459)
Change in intercompany balances	239,112	67,194
Proceeds from merger transaction		646,078
Net cash (used for) provided by investing activities	152,653	713,272
Cash flows from financing activities:
Proceeds from revolving credit facilities	560,000
Reduction in revolving credit facilities	(260,000)	(450,000)
Reduction of long-term debt	(350,000)
Proceeds from (payments for) commercial paper, net	15,000	(162,544)
Proceeds from parent contributions	159,000
Proceeds from issuance of intercompany debt		88,058
Proceeds from term Loan		300,000
Payments on term loan		(300,000)
Net cash (used for) provided by financing activities	124,000	(524,486)
Net increase (decrease) in cash and cash equivalents	(2)	5
Cash and cash equivalents, beginning of period	10	7
Cash and cash equivalents, end of period	8	12
Reportable Legal Entities | Other Subsidiaries (Non-Guarantors)
Condensed Consolidating Statements Of Cash Flows
Net cash provided by (used for) operating activities	669,063	782,139
Cash flows from investing activities:
Purchases of investments	(24)	(8)
Sales and maturities of investments	643	859
Investment in unconsolidated affiliates	(159,000)	(445)
Capital expenditures	(284,950)	(744,047)
Proceeds from sales of assets and insurance claims	26,597	30,164
Change in intercompany balances	(239,112)	(67,194)
Other	(19)	1,700
Cash paid for acquisition of businesses, net		(57,909)
Proceeds from merger transaction		(1,528)
Net cash (used for) provided by investing activities	(655,865)	(838,408)
Cash flows from financing activities:
Increase (decrease) in cash overdrafts	5	363
Repurchase of common shares	(1,687)	(44,978)
Reduction of long-term debt	(142,625)
Proceeds from parent contributions	86,459	(21,322)
Proceeds from (payments for) short-term borrowings	(6,388)	2,792
Proceeds from issuance of intercompany debt	(25,500)	(135,058)
Paydown of intercompany debt		27,000
Net cash (used for) provided by financing activities	(89,736)	(171,203)
Effect of exchange rate changes on cash and cash equivalents	(1,129)	(21,966)
Net increase (decrease) in cash and cash equivalents	(77,667)	(249,438)
Cash and cash equivalents, beginning of period	253,647	499,972
Cash and cash equivalents, end of period	175,980	250,534
Consolidating Adjustments
Condensed Consolidating Statements Of Cash Flows
Net cash provided by (used for) operating activities	(5,960)	(28,303)
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:
Dividends to shareholders	5,960	6,981
Proceeds from parent contributions	(245,459)	21,322
Dividends to shareholders	(5,960)	(6,981)
Net cash (used for) provided by financing activities	$ (239,499)	$ 28,303