CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Restricted Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2012	$ 565,670	$ 1	$ 18,062	$ 67,422	$ 566,318	$ (86,133)
Beginning Balance (in shares) at Dec. 31, 2012		83,320	522
Net income	219,658				219,658
Other comprehensive loss, net of tax	(68,170)					(68,170)
Excess tax benefits on stock-based compensation plans	656		$ 656
Restricted stock activity	4,732		$ 4,732
Restricted stock activity (in shares)		194	(21)
Dividends	0	$ 0	$ 0	0	0	0
Ending Balance at Dec. 31, 2013	722,546	$ 1	$ 23,450	67,422	785,976	(154,303)
Ending Balance (in shares) at Dec. 31, 2013		83,514	501
Net income	249,740				249,740
Other comprehensive loss, net of tax	(31,941)					(31,941)
Excess tax benefits on stock-based compensation plans	1,028		$ 1,028
Restricted stock activity	6,457		$ 6,457
Restricted stock activity (in shares)		228	63
Dividends	0	$ 0	$ 0	0	0	0
Ending Balance at Dec. 31, 2014	947,830	$ 1	$ 30,935	67,422	1,035,716	(186,244)
Ending Balance (in shares) at Dec. 31, 2014		83,742	564
Net income	252,526				252,526
Other comprehensive loss, net of tax	(49,365)					(49,365)
Excess tax benefits on stock-based compensation plans	257		$ 257
Restricted stock activity	7,197		$ 7,197
Restricted stock activity (in shares)		205	(99)
Dividends	0	$ 0	$ 0	0	0	0
Ending Balance at Dec. 31, 2015	$ 1,158,445	$ 1	$ 38,389	$ 67,422	$ 1,288,242	$ (235,609)
Ending Balance (in shares) at Dec. 31, 2015		83,947	465