Condensed Consolidating Statement Of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating activities:
Net income	$ 5.1	$ 66.5
Non-cash expenses	35.1	24.4
Equity in (earnings) loss of subsidiaries
Changes in working capital	11.2	(89.4)
Net adjustments	46.3	(65.0)
Net cash provided by (used in) operating activities	51.4	1.5
Investing activities:
Net cash provided by (used in) investing activities	(7.4)	(17.8)
Financing activities:
Net cash provided by (used in) financing activities	(35.0)	(11.3)
Net decrease in cash and cash equivalents	9.0	(27.6)
Effect of exchange rates	(4.1)	(0.2)
Net change in cash and cash equivalents	4.9	(27.8)
Cash and cash equivalents- beginning of period	70.8	61.3
Cash and cash equivalents- end of period	75.7	33.5
Parent
Operating activities:
Net income	9.0	68.8
Non-cash expenses	(0.1)	18.0
Equity in (earnings) loss of subsidiaries	(27.7)	(133.0)
Changes in working capital	626.2	9.0
Net adjustments	598.4	(106.0)
Net cash provided by (used in) operating activities	607.4	(37.2)
Investing activities:
Net cash provided by (used in) investing activities	494.6	(2.2)
Financing activities:
Net cash provided by (used in) financing activities	(1,097.2)	38.9
Net decrease in cash and cash equivalents	4.8	(0.5)
Effect of exchange rates
Net change in cash and cash equivalents	4.8	(0.5)
Cash and cash equivalents- beginning of period	0.2	3.0
Cash and cash equivalents- end of period	5.0	2.5
Joseph T. Ryerson
Operating activities:
Net income	34.7	97.2
Non-cash expenses	21.7	1.6
Equity in (earnings) loss of subsidiaries	(9.6)	(29.3)
Changes in working capital	1,024.9	(42.8)
Net adjustments	1,037.0	(70.5)
Net cash provided by (used in) operating activities	1,071.7	26.7
Investing activities:
Net cash provided by (used in) investing activities	(577.9)	(18.0)
Financing activities:
Net cash provided by (used in) financing activities	(498.7)	(11.9)
Net decrease in cash and cash equivalents	(4.9)	(3.2)
Effect of exchange rates	0.2
Net change in cash and cash equivalents	(4.7)	(3.2)
Cash and cash equivalents- beginning of period	15.3	14.5
Cash and cash equivalents- end of period	10.6	11.3
Guarantor Subsidiaries
Operating activities:
Net income	8.8	62.1
Non-cash expenses	1.5	1.2
Equity in (earnings) loss of subsidiaries	3.9	(0.6)
Changes in working capital	(1,650.6)	(33.3)
Net adjustments	(1,645.2)	(32.7)
Net cash provided by (used in) operating activities	(1,636.4)	29.4
Investing activities:
Net cash provided by (used in) investing activities	1,458.0	(29.5)
Financing activities:
Net cash provided by (used in) financing activities	179.6	(0.4)
Net decrease in cash and cash equivalents	1.2	(0.5)
Effect of exchange rates
Net change in cash and cash equivalents	1.2	(0.5)
Cash and cash equivalents- beginning of period	1.9	1.5
Cash and cash equivalents- end of period	3.1	1.0
Non-Guarantor Subsidiaries
Operating activities:
Net income	(14.0)	1.3
Non-cash expenses	12.0	3.6
Equity in (earnings) loss of subsidiaries
Changes in working capital	10.7	(22.3)
Net adjustments	22.7	(18.7)
Net cash provided by (used in) operating activities	8.7	(17.4)
Investing activities:
Net cash provided by (used in) investing activities	(2.1)	2.5
Financing activities:
Net cash provided by (used in) financing activities	1.3	(8.5)
Net decrease in cash and cash equivalents	7.9	(23.4)
Effect of exchange rates	(4.3)	(0.2)
Net change in cash and cash equivalents	3.6	(23.6)
Cash and cash equivalents- beginning of period	53.4	42.3
Cash and cash equivalents- end of period	57.0	18.7
Eliminations
Operating activities:
Net income	(33.4)	(162.9)
Non-cash expenses
Equity in (earnings) loss of subsidiaries	33.4	162.9
Changes in working capital
Net adjustments	33.4	162.9
Net cash provided by (used in) operating activities
Investing activities:
Net cash provided by (used in) investing activities	(1,380.0)	29.4
Financing activities:
Net cash provided by (used in) financing activities	1,380.0	(29.4)
Net decrease in cash and cash equivalents
Effect of exchange rates
Net change in cash and cash equivalents
Cash and cash equivalents- beginning of period
Cash and cash equivalents- end of period