CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Paid-in capital	Treasury stock	Accumulated other comprehensive income (loss)	Retained earnings (deficit)
Balance, beginning of period at Dec. 31, 2014		$ 340,047	$ 1,663,592	$ (32,937)	$ (81,341)	$ (852,458)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net common stock issued under share-based compensation plans		44	(446)
Issuance of common stock (note 13)		0	0
Reissuance of treasury stock, net			(6,894)	29,575		(29,494)
Tax benefit from share-based compensation			2,113
Equity compensation			8,942
Reacquisition of convertible junior subordinated debentures-equity component (note 3)			0
Purchases of common stock (note 13)				0
Other comprehensive income (loss), net of tax (note 9)	$ 38,194				38,194
Net income	1,069,582					1,069,582
Balance, end of period at Sep. 30, 2015	2,148,519	340,091	1,667,307	(3,362)	(43,147)	187,630
Balance, beginning of period at Dec. 31, 2015	2,236,140	340,097	1,670,238	(3,362)	(60,880)	290,047
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net common stock issued under share-based compensation plans		985	(5,989)
Issuance of common stock (note 13)		18,313	113,146
Reissuance of treasury stock, net			0	0		0
Tax benefit from share-based compensation			100
Equity compensation			8,753
Reacquisition of convertible junior subordinated debentures-equity component (note 3)			(6,337)
Purchases of common stock (note 13)	(108,100)			(108,097)
Other comprehensive income (loss), net of tax (note 9)	91,035				91,035
Net income	235,030					235,030
Balance, end of period at Sep. 30, 2016	$ 2,583,079	$ 359,395	$ 1,779,911	$ (111,459)	$ 30,155	$ 525,077