Consolidated Statements of Changes in Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance (in shares) at Dec. 31, 2015		62,803
Beginning Balance at Dec. 31, 2015	$ 992,590	$ 125,606	$ 211,943	$ 706,866	$ (51,825)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	108,787			108,787
Other comprehensive loss	(15,658)				(15,658)
Dividends declared ($0.86 per share for 2018, $1.03 per share for 2017, $1.02 per share for 2016)	$ (63,212)			(63,212)
Shares repurchased and retired (in shares)	(2,000)	(2,045)
Shares repurchased and retired	$ (71,028)	$ (4,091)		(66,937)
Share-based compensation expense, exercises and other (in shares)		273
Share-based compensation expense, exercises and other	8,559	$ 547	8,012
Ending Balance (in shares) at Dec. 31, 2016		61,031
Ending Balance at Dec. 31, 2016	960,038	$ 122,062	219,955	685,504	(67,483)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	72,793			72,793
Other comprehensive loss	42,399				42,399
Dividends declared ($0.86 per share for 2018, $1.03 per share for 2017, $1.02 per share for 2016)	$ (62,933)			(62,933)
Shares repurchased and retired (in shares)	(200)	(155)
Shares repurchased and retired	$ (5,000)	$ (310)		(4,690)
Share-based compensation expense, exercises and other (in shares)		600
Share-based compensation expense, exercises and other	$ 8,182	$ 1,200	6,982
Ending Balance (in shares) at Dec. 31, 2017	61,476	61,476
Ending Balance at Dec. 31, 2017	$ 1,015,479	$ 122,952	226,937	690,674	(25,084)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(437,012)
Other comprehensive loss	(20,528)
Dividends declared ($0.86 per share for 2018, $1.03 per share for 2017, $1.02 per share for 2016)	(52,992)			(52,992)
Share-based compensation expense, exercises and other (in shares)		818
Share-based compensation expense, exercises and other	$ 13,472	$ 1,636	11,836
Ending Balance (in shares) at Dec. 31, 2018	62,294	62,294
Ending Balance at Dec. 31, 2018	$ 518,419	$ 124,588	$ 238,773	$ 200,670	$ (45,612)