Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows From Operating Activities:
Net income	$ 103,000	$ 70,800	$ 53,700
Reconciling adjustments:
Depreciation and amortization	83,400	69,700	69,700
Deferred income taxes	50,700	2,700	57,500
Loss (gain) on disposal of property	1,200	(1,500)	200
Post-retirement expense (income)	2,000	(5,900)	1,600
Share-based compensation expense	12,200	8,700	5,900
Equity in (income) loss of related party Terminal Joint Venture	(16,500)	(6,600)	2,000
Distributions from Terminal Joint Venture	14,000
Tax benefit from equity issuance	2,600	800	1,800
Excess tax benefit from stock-based compensation	(900)	(1,100)	(600)
Changes in assets and liabilities:
Accounts receivable	13,500	(15,300)	(7,600)
Deferred dry-docking payments	(25,700)	(14,100)	(14,000)
Deferred dry-docking amortization	23,100	21,100	22,000
Prepaid expenses and other assets	(13,200)	17,300	(11,800)
Accounts payable and accrued liabilities	(9,400)	13,500	2,200
Other liabilities	5,300	5,600	13,100
Net cash provided by operating activities	245,300	165,700	195,700
Cash Flows From Investing Activities:
Capital expenditures	(67,800)	(27,900)	(35,200)
Proceeds from disposal of property and equipment	5,500	4,900	4,500
Cash deposits into Capital Construction Fund	(77,900)	(31,900)	(4,400)
Withdrawals from Capital Construction Fund	105,400	4,400	4,400
Payments for Horizon's common stock, net of cash acquired, and other acquisitions	(29,000)		(9,300)
Net cash used in investing activities	(63,800)	(50,500)	(40,000)
Cash Flows From Financing Activities:
Proceeds from issuance of debt	75,000	100,000	21,000
Excess tax benefit from stock-based compensation	900	1,100	600
Payments of debt	(20,500)	(11,400)	(45,400)
Payment of capital leases	(1,500)	(1,100)	(1,200)
Proceeds from revolving credit facility	588,000
Payments of revolving credit facility	(588,000)		(11,000)
Payment of financing costs	(900)
Proceeds from issuance of capital stock	2,200	5,800	1,700
Tax withholding related to net share settlements of restricted stock units	(2,900)	(2,000)
Dividends paid	(30,800)	(28,700)	(26,800)
Shares repurchased	(4,900)
Payments of Horizon debt and redemption of warrants, net	(466,000)
Net cash (used in) provided by financing activities	(449,400)	63,700	(61,100)
Net (Decrease) Increase in Cash and Cash Equivalents	(267,900)	178,900	94,600
Cash and cash equivalents, beginning of the period	293,400	114,500	19,900
Cash and cash equivalents, end of the period	25,500	293,400	114,500
Supplemental Cash Flow Information:
Interest paid	17,700	15,200	13,800
Income tax paid (refund)	40,000	30,200	(3,400)
Non-cash Information:
Capital expenditures included in accounts payable and accrued liabilities	13,500	$ 1,600	2,100
Capital lease obligations	$ 1,800		$ 2,900