CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Unaudited) - 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		32	(32)	29,575		(29,496)
Reissuance of treasury stock, net			(7,181)
Tax benefit from share-based compensation			2,568
Equity compensation			5,984
Reacquisition of convertible junior subordinated debentures-equity component			0
Other comprehensive income (loss), net of tax	$ (46,799)				(46,799)
Net income	246,730					246,730
Balance, end of period at Jun. 30, 2015	1,238,284	340,079	1,664,931	(3,362)	(128,140)	(635,224)
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		979	(5,954)	0		0
Reissuance of treasury stock, net			0
Tax benefit from share-based compensation			115
Equity compensation			6,017
Reacquisition of convertible junior subordinated debentures-equity component			(9,750)
Other comprehensive income (loss), net of tax	105,720				105,720
Net income	178,412					178,412
Balance, end of period at Jun. 30, 2016	$ 2,511,679	$ 341,076	$ 1,660,666	$ (3,362)	$ 44,840	$ 468,459